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Re: [ckrm-tech] [RFC][PATCH 3/7] UBC: ub context and inheritance [message #5445 is a reply to message #5371] Sat, 19 August 2006 02:19 Go to previous messageGo to previous message
Matt Helsley is currently offline  Matt Helsley
Messages: 86
Registered: August 2006
Member
On Fri, 2006-08-18 at 13:23 +0400, Kirill Korotaev wrote:
> Matt Helsley wrote:
> > On Wed, 2006-08-16 at 19:38 +0400, Kirill Korotaev wrote:
> >
> >>Contains code responsible for setting UB on task,
> >>it's inheriting and setting host context in interrupts.
> >>
> >>Task references three beancounters:
> >> 1. exec_ub current context. all resources are
> >> charged to this beancounter.
> >
> >
> > nit: 2-3 below seem to contradict "all". If you mean "the rest" then
> > perhaps you ought to reorder these:
> >
> > 1. task_ub ...
> > 2. fork_sub ...
> > 3. exec_ub Current context. Resources not charged to task_ub
> > or fork_sub are charged to this beancounter.
> not sure what you mean.
> task_ub - where _task_ _itself_ is charged as an object.
> following patches will add charging of "number of tasks" using it.
> fork_sub - beancounter which is inherited on fork() (chaning task beancounter).
> exec_ub - is current context.
>
>
> >> 2. task_ub beancounter to which task_struct is
> >> charged itself.
> >
> >
> > Is task_ub frequently the parent beancounter of exec_ub? If it's always
> > the parent then perhaps the one or more of these _ub fields in the task
> > struct are not necessary.
> no, task_ub != exec_ub of parent task
> when task is created anything can happen: task can change ub, parent can change ub,
> task can be reparented. But the UB we charged task to should be known.
>
> > Also in that case keeping copies of the
> > "parent" user_beancounter pointers in the task_beancounters would seem
> > bug-prone -- if the hierarchy of beancounters changes then these would
> > need to be changed too.
> >
> >
> >> 3. fork_sub beancounter which is inherited by
> >> task's children on fork
> >
> >
> > Is this frequently the same as exec_ub?
> frequently, but not always. exec_ub is changed in softirq for example.
> consider exec_ub as 'current' pointer in kernel.
>
> see other comments below
>
> >>Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
> >>Signed-Off-By: Kirill Korotaev <dev@sw.ru>
> >>
> >>---
> >> include/linux/sched.h | 5 +++++
> >> include/ub/task.h | 42 ++++++++++++++++++++++++++++++++++++++++++
> >> kernel/fork.c | 21 ++++++++++++++++-----
> >> kernel/irq/handle.c | 9 +++++++++
> >> kernel/softirq.c | 8 ++++++++
> >> kernel/ub/Makefile | 1 +
> >> kernel/ub/beancounter.c | 4 ++++
> >> kernel/ub/misc.c | 34 ++++++++++++++++++++++++++++++++++
> >> 8 files changed, 119 insertions(+), 5 deletions(-)
> >>
> >>--- ./include/linux/sched.h.ubfork 2006-07-17 17:01:12.000000000 +0400
> >>+++ ./include/linux/sched.h 2006-07-31 16:01:54.000000000 +0400
> >>@@ -81,6 +81,8 @@ struct sched_param {
> >> #include <linux/timer.h>
> >> #include <linux/hrtimer.h>
> >>
> >>+#include <ub/task.h>
> >>+
> >> #include <asm/processor.h>
> >>
> >> struct exec_domain;
> >>@@ -997,6 +999,9 @@ struct task_struct {
> >> spinlock_t delays_lock;
> >> struct task_delay_info *delays;
> >> #endif
> >>+#ifdef CONFIG_USER_RESOURCE
> >>+ struct task_beancounter task_bc;
> >>+#endif
> >> };
> >>
> >> static inline pid_t process_group(struct task_struct *tsk)
> >>--- ./include/ub/task.h.ubfork 2006-07-28 18:53:52.000000000 +0400
> >>+++ ./include/ub/task.h 2006-08-01 15:26:08.000000000 +0400
> >>@@ -0,0 +1,42 @@
> >>+/*
> >>+ * include/ub/task.h
> >>+ *
> >>+ * Copyright (C) 2006 OpenVZ. SWsoft Inc
> >>+ *
> >>+ */
> >>+
> >>+#ifndef __UB_TASK_H_
> >>+#define __UB_TASK_H_
> >>+
> >>+#include <linux/config.h>
> >>+
> >>+struct user_beancounter;
> >>+
> >>+struct task_beancounter {
> >>+ struct user_beancounter *exec_ub;
> >>+ struct user_beancounter *task_ub;
> >>+ struct user_beancounter *fork_sub;
> >>+};
> >>+
> >>+#ifdef CONFIG_USER_RESOURCE
> >>+#define get_exec_ub() (current->task_bc.exec_ub)
> >>+#define set_exec_ub(newub) \
> >>+ ({ \
> >>+ struct user_beancounter *old; \
> >>+ struct task_beancounter *tbc; \
> >>+ tbc = &current->task_bc; \
> >>+ old = tbc->exec_ub; \
> >>+ tbc->exec_ub = newub; \
> >>+ old; \
> >>+ })
> >>+
> >
> >
> > How about making these static inlines?
> possible, but this requires including sched.h, which includes this file...
> so this one is easier and more separated.
>
> >>+int ub_task_charge(struct task_struct *parent, struct task_struct *new);
> >>+void ub_task_uncharge(struct task_struct *tsk);
> >>+
> >>+#else /* CONFIG_USER_RESOURCE */
> >>+#define get_exec_ub() (NULL)
> >>+#define set_exec_ub(__ub) (NULL)
> >>+#define ub_task_charge(p, t) (0)
> >>+#define ub_task_uncharge(t) do { } while (0)
> >>+#endif /* CONFIG_USER_RESOURCE */
> >>+#endif /* __UB_TASK_H_ */
> >>--- ./kernel/irq/handle.c.ubirq 2006-07-10 12:39:20.000000000 +0400
> >>+++ ./kernel/irq/handle.c 2006-08-01 12:39:34.000000000 +0400
> >>@@ -16,6 +16,9 @@
> >> #include <linux/interrupt.h>
> >> #include <linux/kernel_stat.h>
> >>
> >>+#include <ub/beancounter.h>
> >>+#include <ub/task.h>
> >>+
> >> #include "internals.h"
> >>
> >> /**
> >>@@ -166,6 +169,9 @@ fastcall unsigned int __do_IRQ(unsigned
> >> struct irq_desc *desc = irq_desc + irq;
> >> struct irqaction *action;
> >> unsigned int status;
> >>+ struct user_beancounter *ub;
> >>+
> >>+ ub = set_exec_ub(&ub0);
> >
> >
> > Perhaps a comment: "/* Don't charge resources gained in interrupts to current */
> ok, will add comment:
> /* UBC charges should be done to host system */
> >
> >
> >> kstat_this_cpu.irqs[irq]++;
> >> if (CHECK_IRQ_PER_CPU(desc->status)) {
> >>@@ -178,6 +184,8 @@ fastcall unsigned int __do_IRQ(unsigned
> >> desc->chip->ack(irq);
> >> action_ret = handle_IRQ_event(irq, regs, desc->action);
> >> desc->chip->end(irq);
> >>+
> >>+ (void) set_exec_ub(ub);
> >> return 1;
> >> }
> >>
> >>@@ -246,6 +254,7 @@ out:
> >> desc->chip->end(irq);
> >> spin_unlock(&desc->lock);
> >>
> >>+ (void) set_exec_ub(ub);
> >
> >
> >
> > Seems like a WARN_ON() would be appropriate rather than ignoring the
> > return code.
> BUG_ON(ret != &ub0) ?

Oops, yes, it's not a return code and BUG_ON() does seem more
appropriate.

>
> maybe introduce a kind of
> reset_exec_ub(old_ub, expected_current_ub)
> {
> ret = set_exec_ub(old_ub);
> BUG_ON(ret != expected_current_ub);
> }
> ?

Seems like a good idea to me. This way when UBC is not configured
there'd also be no BUG_ON().

> >> return 1;
> >> }
> >>
> >>--- ./kernel/softirq.c.ubirq 2006-07-17 17:01:12.000000000 +0400
> >>+++ ./kernel/softirq.c 2006-08-01 12:40:44.000000000 +0400
> >>@@ -18,6 +18,9 @@
> >> #include <linux/rcupdate.h>
> >> #include <linux/smp.h>
> >>
> >>+#include <ub/beancounter.h>
> >>+#include <ub/task.h>
> >>+
> >> #include <asm/irq.h>
> >> /*
> >> - No shared variables, all the data are CPU local.
> >>@@ -191,6 +194,9 @@ asmlinkage void __do_softirq(void)
> >> __u32 pending;
> >> int max_restart = MAX_SOFTIRQ_RESTART;
> >> int cpu;
> >>+ struct user_beancounter *ub;
> >>+
> >>+ ub = set_exec_ub(&ub0);
> >
> >
> > Perhaps add the same comment...
> ok
>
> >
> >
> >> pending = local_softirq_pending();
> >> account_system_vtime(current);
> >>@@ -229,6 +235,8 @@ restart:
> >>
> >> account_system_vtime(current);
> >> _local_bh_enable();
> >>+
> >>+ (void) set_exec_ub(ub);
> >
> >
> > .. and the same WARN_ON.
> >
> >
> >> }
> >>
> >> #ifndef __ARCH_HAS_DO_SOFTIRQ
> >>--- ./kernel/fork.c.ubfork 2006-07-17 17:01:12.000000000 +0400
> >>+++ ./kernel/fork.c 2006-08-01 12:58:36.000000000 +0400
> >>@@ -46,6 +46,8 @@
> >> #include <linux/delayacct.h>
> >> #include <linux/taskstats_kern.h>
> >>
> >>+#include <ub/task.h>
> >>+
> >> #include <asm/pgtable.h>
> >> #include <asm/pgalloc.h>
> >> #include <asm/uaccess.h>
> >>@@ -102,6 +104,7 @@ static kmem_cache_t *mm_cachep;
> >> ...

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