OpenVZ Forum - RDF feed
type: channel
items: [PATCH 0/5] Kernel memory accounting container (v5)
items: [PATCH 1/5] Add notification about some major slab events
items: [PATCH 2/5] Generic notifiers for SLUB events
items: [PATCH 3/5] Switch caches notification dynamically
items: [PATCH 4/5] Setup the control group
items: [PATCH 5/5] Account for the slub objects
items: Re: [PATCH 1/5] Add notification about some major slab events
items: Re: [PATCH 3/5] Switch caches notification dynamically
items: Re: [PATCH 2/5] Generic notifiers for SLUB events
items: Re: [PATCH 4/5] Setup the control group
items: Re: [PATCH 5/5] Account for the slub objects
items: Re: [PATCH 0/5] Kernel memory accounting container (v5)
items: Re: Re: [PATCH 4/5] Setup the control group

[PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Changes since v.4: * make SLAB_NOTIFY caches mark pages as SlabDebug. That makes the interesting paths simpler (thanks to Christoph); * the change above caused appropriate changes in "turn notifications on" path - all available pages must become SlabDebug and page's freelists must be flushed; * added two more events - "on" and "off" to make kmalloc caches disabling more gracefully; * turning notifications "off" is marked as "TODO". Right now it's hard w/o massive rework of slub.c in respect to full slabs handling. Changes since v.3: * moved alloc/free notification into slow path and make "notify-able" caches walk this path always; * introduced some optimization for the case, when there's only one listener for SLUB events (saves more that 10% of performance); * ported on 2.6.23-rc6-mm1 tree. Changes since v.2: * introduced generic notifiers for slub. right now there are only events, needed by accounting, but this set can be extended in the future; * moved the controller core into separate file, so that its extension and/or porting on slAb will look more logical; * fixed this message :). Changes since v.1: * fixed Paul's comment about subsystem registration; * return ERR_PTR from ->create callback, not NULL; * make container-to-object assignment in rcu-safe section; * make turning accounting on and off with "1" and "0". ============================================================ Long time ago we decided to start memory control with the user memory container. Now this container in -mm tree and I think we can start with the kmem one. First of all - why do we need this kind of control. The major "pros" is that kernel memory control protects the system from DoS attacks by processes that live in container. As our experience shows many exploits simply do not work in the container with limited kernel memory. I can split the kernel memory container into 4 parts: 1. kmalloc-ed objects control 2. vmalloc-ed objects control 3. buddy allocated pages control 4. kmem_cache_alloc-e…
creator: Pavel Emelianov
date: 2007-09-25T14:16:33-00:00

[PATCH 1/5] Add notification about some major slab events
type: item
description: According to Christoph, there are already multiple people who want to control slab allocations and track memory for various reasons. So this is an introduction of such a hooks. Currently, functions that are to call the notifiers are empty and marked as "weak". Thus, if there's only _one_ listener to these events, it can happily link with the vmlinux and handle the events with more than 10% of performance saved. The events tracked are: 1. allocation of an object; 2. freeing of an object; 3. allocation of a new page for objects; 4. freeing this page. More events can be added on demand. The kmem cache marked with SLAB_NOTIFY flag will cause all the events above to generate notifications. By default no caches come with this flag. The events are generated on slow paths only and as soon as the cache is marked as SLAB_NOTIFY, it will always use them for allocation. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> --- diff --git a/include/linux/slab.h b/include/linux/slab.h index f3a8eec..68d8e65 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -28,6 +28,7 @@ #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ +#define SLAB_NOTIFY 0x00400000UL /* Notify major events */ /* The following flags affect the page allocator grouping pages by mobility */ #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */ diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 40801e7..8cfd9ff 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -200,4 +203,22 @@ static __always_inline void *kmalloc_nod } #endif +struct slub_notify_struct { + struct kmem_cache *cachep; + void *objp; + gfp_t gfp; +}; + +enum { + SLUB_ON, + SLUB_OFF, + SLUB_ALLOC, + SLUB_FREE, + SLUB_NEWPAGE, + SLUB_FREEPAGE, +}; + +int slub_register_notifier(struct notifier_block *nb); +void slub_unregist…
creator: Pavel Emelianov
date: 2007-09-25T14:18:00-00:00

[PATCH 2/5] Generic notifiers for SLUB events
type: item
description: If the user wants more than one listener for SLUB event, it can register them all as notifier_block-s so all of them will be notified. This costs us about 10% of performance loss, in comparison with static linking. The selected method of notification is srcu notifier blocks. This is selected because the "call" path, i.e. when the notification is done, is lockless and at the same time the handlers can sleep. Neither regular nor atomic notifiers provide such facilities. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> --- diff --git a/init/Kconfig b/init/Kconfig index 684ccfb..e9acc29 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -593,6 +599,16 @@ config SLUB_DEBUG SLUB sysfs support. /sys/slab will not exist and there will be no support for cache validation etc. +config SLUB_NOTIFY + default y + bool "Enable SLUB events generic notification" + depends on SLUB + help + When Y, this option enables generic notifications of some major + slub events. However, if you do know that there will be the + only listener for them, you may say N here, so that callbacks + will be called directly. + choice prompt "Choose SLAB allocator" default SLUB diff --git a/mm/slub.c b/mm/slub.c index 31d04a3..e066a0e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1040,6 +1040,89 @@ static inline unsigned long kmem_cache_f * notifiers */ +#ifdef CONFIG_SLUB_NOTIFY +static struct srcu_notifier_head slub_nb; + +static noinline +int __slub_notify_fail(int cmd_alloc, int cmd_free, struct kmem_cache *cachep, + void *obj, gfp_t gfp) +{ + int ret, called = 0; + struct slub_notify_struct arg; + + arg.cachep = cachep; + arg.objp = obj; + arg.gfp = gfp; + + ret = __srcu_notifier_call_chain(&slub_nb, cmd_alloc, &arg, + -1, &called); + ret = notifier_to_errno(ret); + + if (ret < 0 && called) + __srcu_notifier_call_chain(&slub_nb, cmd_free, &arg, + called - 1, NULL); + + return ret; +} + +static noinline +void __slub_notify(int cmd, struct kmem_cache *cachep, void *obj) +{ + struct slub_notify_struct arg; + +…
creator: Pavel Emelianov
date: 2007-09-25T14:19:05-00:00

[PATCH 3/5] Switch caches notification dynamically
type: item
description: The /sys/slab/<name>/cache_notify attribute controls whether the cache <name> is to be accounted or not. By default no caches are accountable. Simply make # echo -n 1 > /sys/slab/<name>cache_notify to turn notification of this cache on. If we turn accounting on on some cache and this cache is merged with some other, this "other" will be notified as well. One can solve this by disabling of cache merging, i.e. booting with slub_nomerge option to the kernel. Turning the notifications "on" causes all te subsequent allocations use the slow allocation path, so all the per-cpu caches are flushed and all the partial pages are marked as SlabDebug. Turning the notification off is possible only when this cache is empty. The reason for this is that the pages, that are full of objects are not linked in any list, so we wouldn't be able to walk these pages and tell them thay should not produce notifications any longer. To make "off" possible we need to rework the slub.c in respect to full slabs handling (this is currently available with SLUB_DEBUG only). This is in TODO. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> --- diff --git a/mm/slub.c b/mm/slub.c index 31d04a3..e066a0e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3779,6 +3932,60 @@ static ssize_t defrag_ratio_store(struct SLAB_ATTR(defrag_ratio); #endif +static ssize_t cache_notify_show(struct kmem_cache *s, char *buf) +{ + return sprintf(buf, "%d\n", !!(s->flags & SLAB_NOTIFY)); +} + +static ssize_t cache_notify_store(struct kmem_cache *s, + const char *buf, size_t length) +{ + int err; + int n; + + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { + err = slub_on_notify(s); + if (err < 0) + return err; + + s->flags |= SLAB_NOTIFY; + + flush_all(s); + for_each_node_state(n, N_NORMAL_MEMORY) { + struct kmem_cache_node *node; + struct page *pg; + + node = get_node(s, n); + spin_lock_irq(&node->list_lock); + list_for_each_entry(pg, &node->partial, lru) + SetSlabDebug(pg); + spin_unlock_irq(&node->list_lock); + } + return…
creator: Pavel Emelianov
date: 2007-09-25T14:22:51-00:00

[PATCH 4/5] Setup the control group
type: item
description: Attach the controller to the control groups. This will work with the SLUB allocator only. However, if we need I can port this on SLAB (and maybe SLOB ;) ). This setup is simple and stupid. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> --- diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h index d822977..bd0f493 100644 --- a/include/linux/cgroup_subsys.h +++ b/include/linux/cgroup_subsys.h @@ -36,3 +36,9 @@ SUBSYS(mem_cgroup) #endif /* */ + +#ifdef CONFIG_CGROUP_KMEM +SUBSYS(kmem) +#endif + +/* */ diff --git a/init/Kconfig b/init/Kconfig index 684ccfb..e9acc29 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -353,6 +353,12 @@ config CGROUP_MEM_CONT Provides a memory controller that manages both page cache and RSS memory. +config CGROUP_KMEM + bool "Kernel memory controller for containers" + depends on CGROUPS && RESOURCE_COUNTERS && SLUB + help + Provides a kernel memory usage control for containers + config PROC_PID_CPUSET bool "Include legacy /proc/<pid>/cpuset file" depends on CPUSETS diff --git a/mm/kmemcontrol.c b/mm/kmemcontrol.c new file mode 100644 index 0000000..5698c0f --- /dev/null +++ b/mm/kmemcontrol.c @@ -0,0 +1,119 @@ +/* + * kmemcontrol.c - Kernel Memory Controller + * + * Copyright 2007 OpenVZ SWsoft Inc + * Author: Pavel Emelyanov <xemul@openvz.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/mm.h> +#include <linux/cgroup.h> +#include <linux/res_counter.h> +#include <linux/err.h> + +struct kmem_container { + struct cgroup_subsys_state css;…
creator: Pavel Emelianov
date: 2007-09-25T14:24:30-00:00

[PATCH 5/5] Account for the slub objects
type: item
description: The struct page gets an extra pointer (just like it has with the RSS controller) and this pointer points to the array of the kmem_container pointers - one for each object stored on that page itself. Thus the i'th object on the page is accounted to the container pointed by the i'th pointer on that array and when the object is freed we unaccount its size to this particular container, not the container current task belongs to. This is done so, because the context objects are freed is most often not the same as the one this objects was allocated in (due to RCU and reference counters). This controller disables the kmalloc caches accounting, since we cannot just track all the kmalloc calls, but we need to explicitly specify which kmalloc do we want to account for with (e.g.) additional GFP flag. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> --- diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index f83bd17..8e1ef21 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -83,9 +83,14 @@ struct page { void *virtual; /* Kernel virtual address (NULL if not kmapped, ie. highmem) */ #endif /* WANT_PAGE_VIRTUAL */ + union { #ifdef CONFIG_CGROUP_MEM_CONT - unsigned long page_cgroup; + unsigned long page_cgroup; +#endif +#ifdef CONFIG_CGROUP_KMEM + struct kmem_container **cgroups; #endif + }; #ifdef CONFIG_PAGE_OWNER int order; unsigned int gfp_mask; diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h index 40801e7..8cfd9ff 100644 --- a/include/linux/slub_def.h +++ b/include/linux/slub_def.h @@ -69,6 +69,9 @@ struct kmem_cache { #endif }; +int slab_index(void *p, struct kmem_cache *s, void *addr); +int is_kmalloc_cache(struct kmem_cache *s); + /* * Kmalloc subsystem. */ diff --git a/mm/Makefile b/mm/Makefile index 81232a1..f7ec4b7 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -31,4 +31,5 @@ obj-$(CONFIG_MIGRATION) += migrate.o obj-$(CONFIG_SMP) += allocpercpu.o obj-$(CONFIG_QUICKLIST) += quicklist.o obj-$(CONFIG_CGROUP_MEM_CONT) += …
creator: Pavel Emelianov
date: 2007-09-25T14:26:18-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: On Tue, 25 Sep 2007, Pavel Emelyanov wrote: > @@ -28,6 +28,7 @@ > #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ > #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ > #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ > +#define SLAB_NOTIFY 0x00400000UL /* Notify major events */ > You need to add SLAB_NOTIFY to the SLUB_NEVER_MERGE group. That way you can solve the merging issue. Otherwise this looks okay now.
creator: Christoph Lameter
date: 2007-09-25T21:47:00-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: On Tue, 25 Sep 2007, Pavel Emelyanov wrote: > + for_each_node_state(n, N_NORMAL_MEMORY) { > + struct kmem_cache_node *node; > + struct page *pg; > + > + node = get_node(s, n); > + spin_lock_irq(&node->list_lock); > + list_for_each_entry(pg, &node->partial, lru) > + SetSlabDebug(pg); > + spin_unlock_irq(&node->list_lock); Is it necessary to mark all the existing slabs with SLAB_DEBUG? Would it not be sufficient to just mark the new ones coming up? The above operation could be a bit expensive.
creator: Christoph Lameter
date: 2007-09-25T21:48:59-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Christoph Lameter wrote: > On Tue, 25 Sep 2007, Pavel Emelyanov wrote: > >> @@ -28,6 +28,7 @@ >> #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ >> #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ >> #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ >> +#define SLAB_NOTIFY 0x00400000UL /* Notify major events */ >> > > You need to add SLAB_NOTIFY to the SLUB_NEVER_MERGE group. That way you > can solve the merging issue. True, but we mark the slubs as notifyable at runtime, after they are merged. However, once someone decides to make his slab notifyable from the very beginning this makes sense, thanks. > Otherwise this looks okay now. Oh, great! Does this mean I can put Acked-by when sending this to Andrew? Thanks, Pavel
creator: Pavel Emelianov
date: 2007-09-26T09:37:31-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Christoph Lameter wrote: > On Tue, 25 Sep 2007, Pavel Emelyanov wrote: > >> + for_each_node_state(n, N_NORMAL_MEMORY) { >> + struct kmem_cache_node *node; >> + struct page *pg; >> + >> + node = get_node(s, n); >> + spin_lock_irq(&node->list_lock); >> + list_for_each_entry(pg, &node->partial, lru) >> + SetSlabDebug(pg); >> + spin_unlock_irq(&node->list_lock); > > > Is it necessary to mark all the existing slabs with SLAB_DEBUG? Would it Yup. Otherwise we can never receive a single event e.g. if we make alloc/free in a loop, or similar, so that new slabs simply are not created. > not be sufficient to just mark the new ones coming up? The above operation > could be a bit expensive. Oh, that's OK from my POV - switching slabs mode was never supposed to be a fast path. Thanks, Pavel
creator: Pavel Emelianov
date: 2007-09-26T09:39:21-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: On Wed, 26 Sep 2007, Pavel Emelyanov wrote: > > Is it necessary to mark all the existing slabs with SLAB_DEBUG? Would it > > Yup. Otherwise we can never receive a single event e.g. if we make > alloc/free in a loop, or similar, so that new slabs simply are not > created. Right but on the other hand: If objects in these slabs are freed then your counters get decremented and may go negative.
creator: Christoph Lameter
date: 2007-09-26T17:30:18-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: On Wed, 26 Sep 2007, Pavel Emelyanov wrote: > True, but we mark the slubs as notifyable at runtime, after they > are merged. However, once someone decides to make his slab notifyable > from the very beginning this makes sense, thanks. This also makes sense if a device driver later creates a new slab. Adding the bit will switch off additional merges for that slab. > Oh, great! Does this mean I can put Acked-by when sending this to Andrew? Yes.
creator: Christoph Lameter
date: 2007-09-26T17:31:08-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Christoph Lameter wrote: > On Wed, 26 Sep 2007, Pavel Emelyanov wrote: > >>> Is it necessary to mark all the existing slabs with SLAB_DEBUG? Would it >> Yup. Otherwise we can never receive a single event e.g. if we make >> alloc/free in a loop, or similar, so that new slabs simply are not >> created. > > Right but on the other hand: If objects in these slabs are freed then your > counters get decremented and may go negative. Nope :) I store a pointer on each accounted object, so if I have a notification about freeing of not-accounted object I will not decrement my counter ;) I think it's too hard (if possible at all) to handle at generic level whether we have notified this particular object allocation to some listener or not, so I'd better leave this for the listener to handle such a case. Thanks, Pavel
creator: Pavel Emelianov
date: 2007-09-27T08:24:09-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Christoph Lameter wrote: > On Wed, 26 Sep 2007, Pavel Emelyanov wrote: > >> True, but we mark the slubs as notifyable at runtime, after they >> are merged. However, once someone decides to make his slab notifyable >> from the very beginning this makes sense, thanks. > > This also makes sense if a device driver later creates a new slab. Adding > the bit will switch off additional merges for that slab. True. I will fix it. Thanks. >> Oh, great! Does this mean I can put Acked-by when sending this to Andrew? > > Yes. Great! Thanks a lot! Pavel
creator: Pavel Emelianov
date: 2007-09-27T08:25:26-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Pavel Emelyanov wrote: > According to Christoph, there are already multiple people who > want to control slab allocations and track memory for various > reasons. So this is an introduction of such a hooks. > > Currently, functions that are to call the notifiers are empty > and marked as "weak". Thus, if there's only _one_ listener > to these events, it can happily link with the vmlinux and > handle the events with more than 10% of performance saved. > Please check that weak objects work across platforms. Please see http://www.ussg.iu.edu/hypermail/linux/kernel/0706.0/0593.html > The events tracked are: > 1. allocation of an object; > 2. freeing of an object; > 3. allocation of a new page for objects; > 4. freeing this page. > > More events can be added on demand. > > The kmem cache marked with SLAB_NOTIFY flag will cause all the > events above to generate notifications. By default no caches > come with this flag. > > The events are generated on slow paths only and as soon as the > cache is marked as SLAB_NOTIFY, it will always use them for > allocation. > > Signed-off-by: Pavel Emelyanov <xemul@openvz.org> > > --- > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index f3a8eec..68d8e65 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -28,6 +28,7 @@ > #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ > #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ > #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ > +#define SLAB_NOTIFY 0x00400000UL /* Notify major events */ > > /* The following flags affect the page allocator grouping pages by mobility */ > #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */ > diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h > index 40801e7..8cfd9ff 100644 > --- a/include/linux/slub_def.h > +++ b/include/linux/slub_def.h > @@ -200,4 +203,22 @@ static __always_inline void *kmalloc_nod > } > #endif > > +struct slub…
creator: Balbir Singh
date: 2007-10-01T11:55:39-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> According to Christoph, there are already multiple people who >> want to control slab allocations and track memory for various >> reasons. So this is an introduction of such a hooks. >> >> Currently, functions that are to call the notifiers are empty >> and marked as "weak". Thus, if there's only _one_ listener >> to these events, it can happily link with the vmlinux and >> handle the events with more than 10% of performance saved. >> > > Please check that weak objects work across platforms. Please see > http://www.ussg.iu.edu/hypermail/linux/kernel/0706.0/0593.html OK. >> The events tracked are: >> 1. allocation of an object; >> 2. freeing of an object; >> 3. allocation of a new page for objects; >> 4. freeing this page. >> >> More events can be added on demand. >> >> The kmem cache marked with SLAB_NOTIFY flag will cause all the >> events above to generate notifications. By default no caches >> come with this flag. >> >> The events are generated on slow paths only and as soon as the >> cache is marked as SLAB_NOTIFY, it will always use them for >> allocation. >> >> Signed-off-by: Pavel Emelyanov <xemul@openvz.org> >> >> --- >> >> diff --git a/include/linux/slab.h b/include/linux/slab.h >> index f3a8eec..68d8e65 100644 >> --- a/include/linux/slab.h >> +++ b/include/linux/slab.h >> @@ -28,6 +28,7 @@ >> #define SLAB_DESTROY_BY_RCU 0x00080000UL /* Defer freeing slabs to RCU */ >> #define SLAB_MEM_SPREAD 0x00100000UL /* Spread some memory over cpuset */ >> #define SLAB_TRACE 0x00200000UL /* Trace allocations and frees */ >> +#define SLAB_NOTIFY 0x00400000UL /* Notify major events */ >> >> /* The following flags affect the page allocator grouping pages by mobility */ >> #define SLAB_RECLAIM_ACCOUNT 0x00020000UL /* Objects are reclaimable */ >> diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h >> index 40801e7..8cfd9ff 100644 >> --- a/include/linux/slub_def.h >> +++ b/include/linux/slub_def.h >> @@ -200,4 +20…
creator: Pavel Emelianov
date: 2007-10-01T12:13:43-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Pavel Emelyanov wrote: >> harsh, hard to review since the definition of the above function >> is not known. > > What do you mean by "not known"? I is declared above :) > I meant, we only know the stub weak functions. Does slub_*_notify fail only on fatal errors? If not, then the failure might be unfair. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T12:32:50-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >>> harsh, hard to review since the definition of the above function >>> is not known. >> What do you mean by "not known"? I is declared above :) >> > > I meant, we only know the stub weak functions. Does slub_*_notify > fail only on fatal errors? If not, then the failure might be It depends on the listener of the event when to fail. The slub notification mechanism is not the accounting at all it just sends notifications. > unfair. >
creator: Pavel Emelianov
date: 2007-10-01T12:57:18-00:00

Re: [PATCH 1/5] Add notification about some major slab events
type: item
description: Pavel Emelyanov wrote: > Balbir Singh wrote: >> Pavel Emelyanov wrote: >>>> harsh, hard to review since the definition of the above function >>>> is not known. >>> What do you mean by "not known"? I is declared above :) >>> >> I meant, we only know the stub weak functions. Does slub_*_notify >> fail only on fatal errors? If not, then the failure might be > > It depends on the listener of the event when to fail. The slub > notification mechanism is not the accounting at all it just > sends notifications. > OK. My concern is that a listener can fail allocation of a slub object. >> unfair. >> > -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T13:03:27-00:00

Re: [PATCH 2/5] Generic notifiers for SLUB events
type: item
description: Pavel Emelyanov wrote: > If the user wants more than one listener for SLUB event, > it can register them all as notifier_block-s so all of > them will be notified. > > This costs us about 10% of performance loss, in comparison > with static linking. > > The selected method of notification is srcu notifier blocks. > This is selected because the "call" path, i.e. when the > notification is done, is lockless and at the same time the > handlers can sleep. Neither regular nor atomic notifiers > provide such facilities. > > Signed-off-by: Pavel Emelyanov <xemul@openvz.org> > > --- > > diff --git a/init/Kconfig b/init/Kconfig > index 684ccfb..e9acc29 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -593,6 +599,16 @@ config SLUB_DEBUG > SLUB sysfs support. /sys/slab will not exist and there will be > no support for cache validation etc. > > +config SLUB_NOTIFY > + default y Should the default be on? Shouldn't it depend on KMEM? > + bool "Enable SLUB events generic notification" > + depends on SLUB > + help > + When Y, this option enables generic notifications of some major > + slub events. However, if you do know that there will be the > + only listener for them, you may say N here, so that callbacks > + will be called directly. > + > - > - > +#ifdef CONFIG_SLUB_NOTIFY > + srcu_init_notifier_head(&slub_nb); Can we get rid of the #ifdef CONFIG_SLUB_NOTIFY? > +#endif > printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d," > " CPUs=%d, Nodes=%d\n", > caches, cache_line_size(), > -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T13:05:07-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Pavel Emelyanov wrote: > The /sys/slab/<name>/cache_notify attribute controls > whether the cache <name> is to be accounted or not. > > By default no caches are accountable. Simply make > # echo -n 1 > /sys/slab/<name>cache_notify > to turn notification of this cache on. > > If we turn accounting on on some cache and this cache > is merged with some other, this "other" will be notified > as well. One can solve this by disabling of cache merging, > i.e. booting with slub_nomerge option to the kernel. > > Turning the notifications "on" causes all te subsequent > allocations use the slow allocation path, so all the > per-cpu caches are flushed and all the partial pages > are marked as SlabDebug. > Do we know of the overhead of slub notifications? It would be nice to know and probably add it to the help text in Kconfig. > --- > > diff --git a/mm/slub.c b/mm/slub.c > index 31d04a3..e066a0e 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3779,6 +3932,60 @@ static ssize_t defrag_ratio_store(struct > SLAB_ATTR(defrag_ratio); > #endif > > +static ssize_t cache_notify_show(struct kmem_cache *s, char *buf) > +{ > + return sprintf(buf, "%d\n", !!(s->flags & SLAB_NOTIFY)); > +} > + > +static ssize_t cache_notify_store(struct kmem_cache *s, > + const char *buf, size_t length) > +{ > + int err; > + int n; > + > + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { Won't this code break if I pass 10 as input in buf? > + err = slub_on_notify(s); > + if (err < 0) > + return err; > + > + s->flags |= SLAB_NOTIFY; > + > + flush_all(s); Sounds like an expensive operation, can we add a comment to indicate the same. Also, in the documentation, could we warn the user that turning notifications on/off can be expensive? > + for_each_node_state(n, N_NORMAL_MEMORY) { > + struct kmem_cache_node *node; > + struct page *pg; > + > + node = get_node(s, n); > + spin_lock_irq(&node->list_lock); > + list_for_each_entry(pg, &node->partial, lru) > + SetSlabDebug(pg); > + spin_unlock_irq(&node->list_lock…
creator: Balbir Singh
date: 2007-10-01T13:15:20-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> The /sys/slab/<name>/cache_notify attribute controls >> whether the cache <name> is to be accounted or not. >> >> By default no caches are accountable. Simply make >> # echo -n 1 > /sys/slab/<name>cache_notify >> to turn notification of this cache on. >> >> If we turn accounting on on some cache and this cache >> is merged with some other, this "other" will be notified >> as well. One can solve this by disabling of cache merging, >> i.e. booting with slub_nomerge option to the kernel. >> >> Turning the notifications "on" causes all te subsequent >> allocations use the slow allocation path, so all the >> per-cpu caches are flushed and all the partial pages >> are marked as SlabDebug. >> > > Do we know of the overhead of slub notifications? It would > be nice to know and probably add it to the help text in > Kconfig. When the notification is off the overhead is 0. When they are on it depends on whether we use generic or direct notifications. Roughly: The generic notification costs us up to 10% of performance loss. The direct notification costs us really small, providing the listener is noop. If the listener is doing something - the performance loss can be higher, but how much - depends on the listener :) > >> --- >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 31d04a3..e066a0e 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -3779,6 +3932,60 @@ static ssize_t defrag_ratio_store(struct >> SLAB_ATTR(defrag_ratio); >> #endif >> >> +static ssize_t cache_notify_show(struct kmem_cache *s, char *buf) >> +{ >> + return sprintf(buf, "%d\n", !!(s->flags & SLAB_NOTIFY)); >> +} >> + >> +static ssize_t cache_notify_store(struct kmem_cache *s, >> + const char *buf, size_t length) >> +{ >> + int err; >> + int n; >> + >> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { > > Won't this code break if I pass 10 as input in buf? > >> + err = slub_on_notify(s); >> + if (err < 0) >> + return err; >> + >> + s->flags |= SLAB_NOTIFY; >> …
creator: Pavel Emelianov
date: 2007-10-01T13:19:39-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: >> diff --git a/mm/slub.c b/mm/slub.c >> index 31d04a3..e066a0e 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -3779,6 +3932,60 @@ static ssize_t defrag_ratio_store(struct >> SLAB_ATTR(defrag_ratio); >> #endif >> >> +static ssize_t cache_notify_show(struct kmem_cache *s, char *buf) >> +{ >> + return sprintf(buf, "%d\n", !!(s->flags & SLAB_NOTIFY)); >> +} >> + >> +static ssize_t cache_notify_store(struct kmem_cache *s, >> + const char *buf, size_t length) >> +{ >> + int err; >> + int n; >> + >> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { > > Won't this code break if I pass 10 as input in buf? I don't care about this :) And no /sys/slab/<xxx>/ file does. It's the problem of a user if he pass some shit and doesn't see the notifications turned on/off ;) >> + err = slub_on_notify(s); >> + if (err < 0) >> + return err; >> + >> + s->flags |= SLAB_NOTIFY; >> + >> + flush_all(s); > > Sounds like an expensive operation, can we add a comment > to indicate the same. Also, in the documentation, could > we warn the user that turning notifications on/off > can be expensive? Sure. >> + for_each_node_state(n, N_NORMAL_MEMORY) { >> + struct kmem_cache_node *node; >> + struct page *pg; >> + >> + node = get_node(s, n); >> + spin_lock_irq(&node->list_lock); >> + list_for_each_entry(pg, &node->partial, lru) >> + SetSlabDebug(pg); >> + spin_unlock_irq(&node->list_lock); >> + } >> + return length; >> + } >> + >> + if ((buf[0] == '0') && (s->flags & SLAB_NOTIFY)) { > > What happens if buf is 01? > >> + /* >> + * TODO: make the notifications-off work >> + */ >> + if (any_slab_objects(s)) >> + return -EBUSY; >> + >> + s->flags &= ~SLAB_NOTIFY; >> + err = slub_off_notify(s); >> + if (err < 0) { >> + s->flags |= SLAB_NOTIFY; >> + return err; >> + } >> + >> + return length; >> + } >> + >> + return -EINVAL; >> +} >> + >> +SLAB_ATTR(cache_notify); >> + >> static struct attribute * slab_attrs[] = { >> &slab_size_attr.attr, >> &object_size_attr.attr, >> @@ -3809,6 +4016,7 @@ static str…
creator: Pavel Emelianov
date: 2007-10-01T13:21:58-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: >>> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { >> Won't this code break if I pass 10 as input in buf? > > I don't care about this :) And no /sys/slab/<xxx>/ file does. > It's the problem of a user if he pass some shit and doesn't > see the notifications turned on/off ;) > Well, we don't want confused users? How does a user know what is a valid value to pass? Are you saying that we don't need to care about user interface, if so I don't agree. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T13:38:35-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Balbir Singh wrote: >>>> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { >>> Won't this code break if I pass 10 as input in buf? >> I don't care about this :) And no /sys/slab/<xxx>/ file does. >> It's the problem of a user if he pass some shit and doesn't >> see the notifications turned on/off ;) >> > > Well, we don't want confused users? How does a user know what > is a valid value to pass? Are you saying that we don't need The rules are simple - 1 to turn them on and 0 to turn them off and nothing more. These values user sees when he "cat"s this file. > to care about user interface, if so I don't agree. That's the convention used in the /sys/slab/<x>/ files - the 1 means on the 0 means 0, all the others are not guaranteed :) Thanks, Pavel
creator: Pavel Emelianov
date: 2007-10-01T13:45:46-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Pavel Emelyanov wrote: > Attach the controller to the control groups. This will work > with the SLUB allocator only. However, if we need I can > port this on SLAB (and maybe SLOB ;) ). > > This setup is simple and stupid. > That makes it easier for me to review it:) > +static struct cftype kmem_files[] = { > + { > + .name = "usage", > + .private = RES_USAGE, > + .read = kmem_container_read, > + }, > + { > + .name = "limit", > + .private = RES_LIMIT, > + .write = kmem_container_write, > + .read = kmem_container_read, > + }, > + { > + .name = "failcnt", > + .private = RES_FAILCNT, > + .read = kmem_container_read, > + }, > +}; > + Could we make the user interface similar to the one in the memory controller please! It would make it easier for users to configure and control both. > +static int kmem_populate(struct cgroup_subsys *ss, struct cgroup *cnt) > +{ > + return cgroup_add_files(cnt, ss, kmem_files, ARRAY_SIZE(kmem_files)); > +} > + > +struct cgroup_subsys kmem_subsys = { > + .name = "kmem", > + .create = kmem_create, > + .destroy = kmem_destroy, > + .populate = kmem_populate, > + .subsys_id = kmem_subsys_id, > + .early_init = 1, > +}; > -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T13:48:28-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> Attach the controller to the control groups. This will work >> with the SLUB allocator only. However, if we need I can >> port this on SLAB (and maybe SLOB ;) ). >> >> This setup is simple and stupid. >> > > That makes it easier for me to review it:) :) >> +static struct cftype kmem_files[] = { >> + { >> + .name = "usage", >> + .private = RES_USAGE, >> + .read = kmem_container_read, >> + }, >> + { >> + .name = "limit", >> + .private = RES_LIMIT, >> + .write = kmem_container_write, >> + .read = kmem_container_read, >> + }, >> + { >> + .name = "failcnt", >> + .private = RES_FAILCNT, >> + .read = kmem_container_read, >> + }, >> +}; >> + > > Could we make the user interface similar to the one in the memory > controller please! It would make it easier for users to configure > and control both. Do you mean by merging the similar code or by making them look like the same? If the second, than can you point at least one difference except for "usage" vs "usage_in_bytes" (and similar) naming? >> +static int kmem_populate(struct cgroup_subsys *ss, struct cgroup *cnt) >> +{ >> + return cgroup_add_files(cnt, ss, kmem_files, ARRAY_SIZE(kmem_files)); >> +} >> + >> +struct cgroup_subsys kmem_subsys = { >> + .name = "kmem", >> + .create = kmem_create, >> + .destroy = kmem_destroy, >> + .populate = kmem_populate, >> + .subsys_id = kmem_subsys_id, >> + .early_init = 1, >> +}; >> > >
creator: Pavel Emelianov
date: 2007-10-01T13:51:46-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: Pavel Emelyanov wrote: > The struct page gets an extra pointer (just like it has with > the RSS controller) and this pointer points to the array of > the kmem_container pointers - one for each object stored on > that page itself. > > Thus the i'th object on the page is accounted to the container > pointed by the i'th pointer on that array and when the object > is freed we unaccount its size to this particular container, > not the container current task belongs to. > > This is done so, because the context objects are freed is most > often not the same as the one this objects was allocated in > (due to RCU and reference counters). > > This controller disables the kmalloc caches accounting, since > we cannot just track all the kmalloc calls, but we need to > explicitly specify which kmalloc do we want to account for > with (e.g.) additional GFP flag. > > Signed-off-by: Pavel Emelyanov <xemul@openvz.org> > > --- > > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index f83bd17..8e1ef21 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -83,9 +83,14 @@ struct page { > void *virtual; /* Kernel virtual address (NULL if > not kmapped, ie. highmem) */ > #endif /* WANT_PAGE_VIRTUAL */ > + union { > #ifdef CONFIG_CGROUP_MEM_CONT > - unsigned long page_cgroup; > + unsigned long page_cgroup; > +#endif > +#ifdef CONFIG_CGROUP_KMEM > + struct kmem_container **cgroups; > #endif > + }; > #ifdef CONFIG_PAGE_OWNER > int order; > unsigned int gfp_mask; > diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h > index 40801e7..8cfd9ff 100644 > --- a/include/linux/slub_def.h > +++ b/include/linux/slub_def.h > @@ -69,6 +69,9 @@ struct kmem_cache { > #endif > }; > > +int slab_index(void *p, struct kmem_cache *s, void *addr); > +int is_kmalloc_cache(struct kmem_cache *s); > + > /* > * Kmalloc subsystem. > */ > diff --git a/mm/Makefile b/mm/Makefile > index 81232a1..f7ec4b7 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -31,4 +31,5 …
creator: Balbir Singh
date: 2007-10-01T14:07:27-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: [snip] >> +int slub_alloc_notify(struct kmem_cache *s, void *obj, gfp_t gfp) >> +{ >> + struct page *pg; >> + struct kmem_container *cnt; >> + struct kmem_container **obj_container; >> + >> + pg = virt_to_head_page(obj); >> + obj_container = pg->cgroups; >> + if (unlikely(obj_container == NULL)) { >> + /* >> + * turned on after some objects were allocated >> + */ >> + if (slub_newpage_notify(s, pg, GFP_ATOMIC) < 0) >> + goto err; >> + >> + obj_container = pg->cgroups; >> + } >> + >> + rcu_read_lock(); >> + cnt = task_kmem_container(current); >> + if (res_counter_charge(&cnt->res, s->size)) > > Is s->size measure in pages or bytes? I suspect it is bytes. In bytes, of course :) the struct anon_vma (for example) is difficult to account in pages :P >> + goto err_locked; >> + >> + css_get(&cnt->css); >> + rcu_read_unlock(); >> + obj_container[slab_index(obj, s, page_address(pg))] = cnt; >> + return 0; >> + >> +err_locked: >> + rcu_read_unlock(); >> +err: >> + return -ENOMEM; >> +} >> + >> +void slub_free_notify(struct kmem_cache *s, void *obj) >> +{ >> + struct page *pg; >> + struct kmem_container *cnt; >> + struct kmem_container **obj_container; >> + >> + pg = virt_to_head_page(obj); >> + obj_container = pg->cgroups; >> + if (obj_container == NULL) >> + return; >> + >> + obj_container += slab_index(obj, s, page_address(pg)); >> + cnt = *obj_container; >> + if (cnt == NULL) >> + return; >> + >> + res_counter_uncharge(&cnt->res, s->size); >> + *obj_container = NULL; >> + css_put(&cnt->css); >> +} >> + > > Quick check, slub_free_notify() and slab_alloc_notify() are called > from serialized contexts, right? Yup. >> +int slub_on_notify(struct kmem_cache *cachep) >> +{ >> + return (is_kmalloc_cache(cachep) ? -EINVAL : 0); >> +} >> + > > I know you've mentioned several times in the comments that > kmalloc slab's cannot be accounted for, could you please > add a big comment here as well. This is useless comment - I will implement the kmalloc accounting soon, so it will just go …
creator: Pavel Emelianov
date: 2007-10-01T14:10:11-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Pavel Emelyanov wrote: > Changes since v.4: > * make SLAB_NOTIFY caches mark pages as SlabDebug. That > makes the interesting paths simpler (thanks to Christoph); > * the change above caused appropriate changes in "turn > notifications on" path - all available pages must become > SlabDebug and page's freelists must be flushed; > * added two more events - "on" and "off" to make kmalloc > caches disabling more gracefully; > * turning notifications "off" is marked as "TODO". Right > now it's hard w/o massive rework of slub.c in respect to > full slabs handling. > > Changes since v.3: > * moved alloc/free notification into slow path and make > "notify-able" caches walk this path always; > * introduced some optimization for the case, when there's > only one listener for SLUB events (saves more that 10% > of performance); > * ported on 2.6.23-rc6-mm1 tree. > > Changes since v.2: > * introduced generic notifiers for slub. right now there > are only events, needed by accounting, but this set can > be extended in the future; > * moved the controller core into separate file, so that > its extension and/or porting on slAb will look more > logical; > * fixed this message :). > > Changes since v.1: > * fixed Paul's comment about subsystem registration; > * return ERR_PTR from ->create callback, not NULL; > * make container-to-object assignment in rcu-safe section; > * make turning accounting on and off with "1" and "0". > Hi, Pavel, Overall, the patches look good, except for the comments noted in the other patch postings. I am going to test these patches and see how they hold out. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T14:12:59-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Pavel Emelyanov wrote: > Balbir Singh wrote: >>>>> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { >>>> Won't this code break if I pass 10 as input in buf? >>> I don't care about this :) And no /sys/slab/<xxx>/ file does. >>> It's the problem of a user if he pass some shit and doesn't >>> see the notifications turned on/off ;) >>> >> Well, we don't want confused users? How does a user know what >> is a valid value to pass? Are you saying that we don't need > > The rules are simple - 1 to turn them on and 0 to turn them off > and nothing more. These values user sees when he "cat"s this file. > I think correct error reporting is critical, if the user sets the value to 01 and that ends up disabling slab notifications, the handling is wrong. >> to care about user interface, if so I don't agree. > > That's the convention used in the /sys/slab/<x>/ files - the > 1 means on the 0 means 0, all the others are not guaranteed :) > Is this documented somewhere or is this interpreted from looking at the code of other file handlers? -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Balbir Singh
date: 2007-10-01T14:14:40-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Pavel Emelyanov wrote: >> Could we make the user interface similar to the one in the memory >> controller please! It would make it easier for users to configure >> and control both. > > Do you mean by merging the similar code or by making them look like > the same? If the second, than can you point at least one difference > except for "usage" vs "usage_in_bytes" (and similar) naming? > I meant similar naming, it makes it is easier if the naming convention is the same. -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T14:16:26-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >>> Could we make the user interface similar to the one in the memory >>> controller please! It would make it easier for users to configure >>> and control both. >> Do you mean by merging the similar code or by making them look like >> the same? If the second, than can you point at least one difference >> except for "usage" vs "usage_in_bytes" (and similar) naming? >> > > I meant similar naming, it makes it is easier if the naming convention > is the same. Ok. It looks like the naming in the memcontrol.c has changed after I copied it from there :) BTW, after Andrew accept these patches I think I will spend some time thinking about how to consolidate the res_counter files. Thanks, Pavel
creator: Pavel Emelianov
date: 2007-10-01T14:17:13-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Pavel Emelyanov wrote: > Balbir Singh wrote: >> Pavel Emelyanov wrote: >>>> Could we make the user interface similar to the one in the memory >>>> controller please! It would make it easier for users to configure >>>> and control both. >>> Do you mean by merging the similar code or by making them look like >>> the same? If the second, than can you point at least one difference >>> except for "usage" vs "usage_in_bytes" (and similar) naming? >>> >> I meant similar naming, it makes it is easier if the naming convention >> is the same. > > Ok. It looks like the naming in the memcontrol.c has changed after I > copied it from there :) > > BTW, after Andrew accept these patches I think I will spend some time > thinking about how to consolidate the res_counter files. > Yes, we need to do that. Paul Menage wanted to pull in resource counters into cgroups. Also, I'd like to be able to share res_counters between container groups or at-least support a hierarchy. We could discuss this at that point and/or send out an RFC to get more comments. > Thanks, > Pavel -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T14:21:42-00:00

Re: [PATCH 4/5] Setup the control group
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> Balbir Singh wrote: >>> Pavel Emelyanov wrote: >>>>> Could we make the user interface similar to the one in the memory >>>>> controller please! It would make it easier for users to configure >>>>> and control both. >>>> Do you mean by merging the similar code or by making them look like >>>> the same? If the second, than can you point at least one difference >>>> except for "usage" vs "usage_in_bytes" (and similar) naming? >>>> >>> I meant similar naming, it makes it is easier if the naming convention >>> is the same. >> Ok. It looks like the naming in the memcontrol.c has changed after I >> copied it from there :) >> >> BTW, after Andrew accept these patches I think I will spend some time >> thinking about how to consolidate the res_counter files. >> > > Yes, we need to do that. Paul Menage wanted to pull in resource counters No, please, no :) Let's have them splitted apart. I think that the resource counter abstraction can be used in other places than the control groups... > into cgroups. Also, I'd like to be able to share res_counters between > container groups or at-least support a hierarchy. We could discuss this > at that point and/or send out an RFC to get more comments. > >> Thanks, >> Pavel > >
creator: Pavel Emelianov
date: 2007-10-01T14:27:27-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> Changes since v.4: >> * make SLAB_NOTIFY caches mark pages as SlabDebug. That >> makes the interesting paths simpler (thanks to Christoph); >> * the change above caused appropriate changes in "turn >> notifications on" path - all available pages must become >> SlabDebug and page's freelists must be flushed; >> * added two more events - "on" and "off" to make kmalloc >> caches disabling more gracefully; >> * turning notifications "off" is marked as "TODO". Right >> now it's hard w/o massive rework of slub.c in respect to >> full slabs handling. >> >> Changes since v.3: >> * moved alloc/free notification into slow path and make >> "notify-able" caches walk this path always; >> * introduced some optimization for the case, when there's >> only one listener for SLUB events (saves more that 10% >> of performance); >> * ported on 2.6.23-rc6-mm1 tree. >> >> Changes since v.2: >> * introduced generic notifiers for slub. right now there >> are only events, needed by accounting, but this set can >> be extended in the future; >> * moved the controller core into separate file, so that >> its extension and/or porting on slAb will look more >> logical; >> * fixed this message :). >> >> Changes since v.1: >> * fixed Paul's comment about subsystem registration; >> * return ERR_PTR from ->create callback, not NULL; >> * make container-to-object assignment in rcu-safe section; >> * make turning accounting on and off with "1" and "0". >> > > Hi, Pavel, > > Overall, the patches look good, except for the comments > noted in the other patch postings. I am going to test > these patches and see how they hold out. > OK, thanks. It's already time to go home now, so I will send them to Andrew tomorrow. Maybe you'll find some more BUGs by that time :) BTW, Acked-by-s from different teams make Andrew more willing to accept the patches ;) Thanks, Pavel
creator: Pavel Emelianov
date: 2007-10-01T15:43:44-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: Balbir Singh wrote: > Pavel Emelyanov wrote: >> Balbir Singh wrote: >>>>>> + if ((buf[0] == '1') && !(s->flags & SLAB_NOTIFY)) { >>>>> Won't this code break if I pass 10 as input in buf? >>>> I don't care about this :) And no /sys/slab/<xxx>/ file does. >>>> It's the problem of a user if he pass some shit and doesn't >>>> see the notifications turned on/off ;) >>>> >>> Well, we don't want confused users? How does a user know what >>> is a valid value to pass? Are you saying that we don't need >> The rules are simple - 1 to turn them on and 0 to turn them off >> and nothing more. These values user sees when he "cat"s this file. >> > > I think correct error reporting is critical, if the user sets > the value to 01 and that ends up disabling slab notifications, > the handling is wrong. This is true for all the /sys/slab/<x>/ files... >>> to care about user interface, if so I don't agree. >> That's the convention used in the /sys/slab/<x>/ files - the >> 1 means on the 0 means 0, all the others are not guaranteed :) >> > > Is this documented somewhere or is this interpreted from looking > at the code of other file handlers? I didn't notice this in any Documentation. Maybe Christoph can clarify this question. _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Pavel Emelianov
date: 2007-10-01T15:45:39-00:00

Re: Re: [PATCH 4/5] Setup the control group
type: item
description: On 10/1/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > > Yes, we need to do that. Paul Menage wanted to pull in resource counters > into cgroups. No, that's not what I wanted - I just wanted to try to cut down the boilerplate required to use resource counters. Ideally it would be as simple as including a call to some function such as "add_res_counter(...)" which would deal with setting up all the cgroup control files, provide handlers, etc. This also helps to keep all the APIs consistent. See the patch that I sent last week entitled "Simplify memory controller and resource counter I/O" for a first step in that direction. > Also, I'd like to be able to share res_counters between > container groups or at-least support a hierarchy. A hierarchy sounds like a good idea. For the sharing, there are two approaches - any subsystem that wants sharing has to implement it itself, or else implement sharing at the control groups level and make it (mostly) transparent to the subsystems. I think I prefer the latter and have been playing with some ways to do this. Paul
creator: Paul Menage
date: 2007-10-01T15:50:04-00:00

Re: Re: [PATCH 4/5] Setup the control group
type: item
description: On 10/1/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > Pavel Emelyanov wrote: > >> Could we make the user interface similar to the one in the memory > >> controller please! It would make it easier for users to configure > >> and control both. > > > > Do you mean by merging the similar code or by making them look like > > the same? If the second, than can you point at least one difference > > except for "usage" vs "usage_in_bytes" (and similar) naming? > > > > I meant similar naming, it makes it is easier if the naming convention > is the same. > I agree with this, but I'd rather see standardization on "limit/usage" rather than "limit_in_bytes/usage_in_bytes". Then the same API can be used for subsystems that use resource counters for things that can't be measured in bytes, e.g. number of tasks. Paul
creator: Paul Menage
date: 2007-10-01T15:52:20-00:00

Re: Re: [PATCH 4/5] Setup the control group
type: item
description: Paul Menage wrote: > On 10/1/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: >> Yes, we need to do that. Paul Menage wanted to pull in resource counters >> into cgroups. > > No, that's not what I wanted - I just wanted to try to cut down the > boilerplate required to use resource counters. Ideally it would be as > simple as including a call to some function such as > "add_res_counter(...)" which would deal with setting up all the cgroup > control files, provide handlers, etc. This also helps to keep all the > APIs consistent. > > See the patch that I sent last week entitled "Simplify memory > controller and resource counter I/O" for a first step in that > direction. > OK. I'll take a closer look >> Also, I'd like to be able to share res_counters between >> container groups or at-least support a hierarchy. > > A hierarchy sounds like a good idea. > > For the sharing, there are two approaches - any subsystem that wants > sharing has to implement it itself, or else implement sharing at the > control groups level and make it (mostly) transparent to the > subsystems. I think I prefer the latter and have been playing with > some ways to do this. > Excellent, I prefer the later as well, but it would mean overheads for controllers not using the hierarchy. If we can come up with a design such that parents<->children can effectively share resources, track them and do so recursively, that would be really nice. > Paul -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
creator: Balbir Singh
date: 2007-10-01T15:53:54-00:00

Re: Re: [PATCH 4/5] Setup the control group
type: item
description: On 10/1/07, Balbir Singh <balbir@linux.vnet.ibm.com> wrote: > > Excellent, I prefer the later as well, but it would mean overheads > for controllers not using the hierarchy. I don't think it would have to with the ideas I've been thinking about - each task would still have a set of pointers to subsystems which could be dereferenced just as quickly. The complexity comes in trying to map a task to its actual cgroup object in a given hierarchy - this would involve a bit more work on the part of the cgroup framework, but wouldn't be a fast path operation. See my mail last week titled "Thoughts on virtualizing task containers". > a design such that parents<->children can effectively share resources, > track them and do so recursively, that would be really nice. I think the recursive tracking would probably need to be supplied by the subsystem rather than by the framework. But there's no reason that multiple subsystems couldn't re-use the same hierarchy code via e.g. resource counters. So when you initialize a resource counter you'd tell it about its parent resource counter, and it would handle the recursion automatically in charge/uncharge. Paul
creator: Paul Menage
date: 2007-10-01T16:04:12-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Hi Pavel, One question about the general design of this - have you tested an approach where rather than tagging each object within the cache with the cgroup that allocated it, you instead have (inside the cache code) a separate cache structure for each cgroup? So the space overheads would go from having a per-object overhead (one pointer per object?) to having a "wastage" overhead (on average half a slab per cgroup). And the time overhead would be the time required to lookup the relevant cache for a cgroup at the start of the allocation operation, and the relevant cache for an object (from its struct page) at deallocation, rather then the time required to update the per-object housekeeping pointer. Each cache would need to be assigned a unique ID, used as an index into a per-cgroup lookup table of localized caches. (This could almost be regarded as a form of kmem_cache namespace). It seems to me that this alternative approach would be a lower memory overhead for people who have the kernel memory controller compiled in but aren't using it, or are only using a few groups. Paul On 9/25/07, Pavel Emelyanov <xemul@openvz.org> wrote: > Changes since v.4: > * make SLAB_NOTIFY caches mark pages as SlabDebug. That > makes the interesting paths simpler (thanks to Christoph); > * the change above caused appropriate changes in "turn > notifications on" path - all available pages must become > SlabDebug and page's freelists must be flushed; > * added two more events - "on" and "off" to make kmalloc > caches disabling more gracefully; > * turning notifications "off" is marked as "TODO". Right > now it's hard w/o massive rework of slub.c in respect to > full slabs handling. > > Changes since v.3: > * moved alloc/free notification into slow path and make > "notify-able" caches walk this path always; > * introduced some optimization for the case, when there's > only one listener for SLUB events (saves more that 10% > of performance); > * ported on 2.6.23-rc6-mm1 tree. > > Changes si…
creator: Paul Menage
date: 2007-10-01T16:32:29-00:00

Re: [PATCH 3/5] Switch caches notification dynamically
type: item
description: On Mon, 1 Oct 2007, Balbir Singh wrote: > Is this documented somewhere or is this interpreted from looking > at the code of other file handlers? Documentation/vm/slub.txt _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Christoph Lameter
date: 2007-10-01T20:39:54-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: On Mon, 1 Oct 2007, Pavel Emelyanov wrote: > >> + > > > > Quick check, slub_free_notify() and slab_alloc_notify() are called > > from serialized contexts, right? > > Yup. How is it serialized? _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Christoph Lameter
date: 2007-10-01T20:41:47-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: Christoph Lameter wrote: > On Mon, 1 Oct 2007, Pavel Emelyanov wrote: > >>>> + >>> Quick check, slub_free_notify() and slab_alloc_notify() are called >>> from serialized contexts, right? >> Yup. > > How is it serialized? They are booth called from __slab_alloc()/__slab_free() from under the slab_lock(page). Thanks, Pavel _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Pavel Emelianov
date: 2007-10-02T12:44:08-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Paul Menage wrote: > Hi Pavel, > > One question about the general design of this - have you tested an > approach where rather than tagging each object within the cache with > the cgroup that allocated it, you instead have (inside the cache code) > a separate cache structure for each cgroup? So the space overheads > would go from having a per-object overhead (one pointer per object?) > to having a "wastage" overhead (on average half a slab per cgroup). > And the time overhead would be the time required to lookup the > relevant cache for a cgroup at the start of the allocation operation, > and the relevant cache for an object (from its struct page) at > deallocation, rather then the time required to update the per-object > housekeeping pointer. Such a lookup would require a hastable or something similar. We already have such a bad experience (with OpenVZ RSS fractions accounting for example). Hash lookups imply the CPU caches screwup and hurt the performance. See also the comment below. > Each cache would need to be assigned a unique ID, used as an index > into a per-cgroup lookup table of localized caches. (This could almost > be regarded as a form of kmem_cache namespace). > > It seems to me that this alternative approach would be a lower memory > overhead for people who have the kernel memory controller compiled in > but aren't using it, or are only using a few groups. I thought the same some time ago and tried to make a per-beancounter kmem caches. The result was awful - the memory waste was much larger than in the case of pointer-per-object approach. Let alone the performance questions - each kmalloc required a synchronized hash table lookup that was too bad. If you insist I can try to repeat the experiment, but I'm afraid the result would be the same. > Paul >
creator: Pavel Emelianov
date: 2007-10-02T12:51:10-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: On Tue, 2 Oct 2007, Pavel Emelyanov wrote: > Christoph Lameter wrote: > > On Mon, 1 Oct 2007, Pavel Emelyanov wrote: > > > >>>> + > >>> Quick check, slub_free_notify() and slab_alloc_notify() are called > >>> from serialized contexts, right? > >> Yup. > > > > How is it serialized? > > They are booth called from __slab_alloc()/__slab_free() from under > the slab_lock(page). This means they are serialized per slab. Which means you can guarantee that multiple of these callbacks are not done at the same time for the same object. Is that what you need? _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Christoph Lameter
date: 2007-10-02T18:04:38-00:00

Re: [PATCH 5/5] Account for the slub objects
type: item
description: Christoph Lameter wrote: > On Tue, 2 Oct 2007, Pavel Emelyanov wrote: > >> Christoph Lameter wrote: >>> On Mon, 1 Oct 2007, Pavel Emelyanov wrote: >>> >>>>>> + >>>>> Quick check, slub_free_notify() and slab_alloc_notify() are called >>>>> from serialized contexts, right? >>>> Yup. >>> How is it serialized? >> They are booth called from __slab_alloc()/__slab_free() from under >> the slab_lock(page). > > This means they are serialized per slab. Which means you can guarantee > that multiple of these callbacks are not done at the same time for the > same object. Is that what you need? Yes I know it :) But I do not rely on this lock inside the callbacks. What I need is to notify each new object only once, but this doesn't matter for the callbacks whether there exists some lock or not. In other words - this is just a coincidence that these callbacks are called from under this lock, this was not done deliberately. Fortunately, the rollback in case when the callbacks return an error is done easily under this lock. Thanks, Pavel _______________________________________________ Containers mailing list Containers@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers
creator: Pavel Emelianov
date: 2007-10-03T07:29:13-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: On 10/2/07, Pavel Emelyanov <xemul@openvz.org> wrote: > > Such a lookup would require a hastable or something similar. We already > have such a bad experience (with OpenVZ RSS fractions accounting for > example). Hash lookups imply the CPU caches screwup and hurt the performance. > See also the comment below. I think you could do it with an array lookup if you assigned an index to each cache as it was created, and used that as an offset into a per-cgroup array. > > I thought the same some time ago and tried to make a per-beancounter kmem > caches. The result was awful - the memory waste was much larger than in the > case of pointer-per-object approach. OK, fair enough. Was this with a large number of bean counters? I imagine that with a small number, the waste might be rather more reasonable. Paul
creator: Paul Menage
date: 2007-10-05T07:11:30-00:00

Re: [PATCH 0/5] Kernel memory accounting container (v5)
type: item
description: Paul Menage wrote: > On 10/2/07, Pavel Emelyanov <xemul@openvz.org> wrote: >> Such a lookup would require a hastable or something similar. We already >> have such a bad experience (with OpenVZ RSS fractions accounting for >> example). Hash lookups imply the CPU caches screwup and hurt the performance. >> See also the comment below. > > I think you could do it with an array lookup if you assigned an index > to each cache as it was created, and used that as an offset into a > per-cgroup array. > >> I thought the same some time ago and tried to make a per-beancounter kmem >> caches. The result was awful - the memory waste was much larger than in the >> case of pointer-per-object approach. > > OK, fair enough. > > Was this with a large number of bean counters? I imagine that with a > small number, the waste might be rather more reasonable. Yup. I do not remember the exact number, but this model didn't scale well enough in respect to the number of beancounters. > Paul >
creator: Pavel Emelianov
date: 2007-10-05T13:17:48-00:00