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Re: [PATCH v5 06/14] memcg: kmem controller infrastructure [message #48440 is a reply to message #48398]

Wed, 17 October 2012 22:12

akpm
Messages: 224
Registered: March 2007

Senior Member

On Tue, 16 Oct 2012 14:16:43 +0400
Glauber Costa <glommer@parallels.com> wrote:

> This patch introduces infrastructure for tracking kernel memory pages to
> a given memcg. This will happen whenever the caller includes the flag
> __GFP_KMEMCG flag, and the task belong to a memcg other than the root.
>
> In memcontrol.h those functions are wrapped in inline acessors. The
> idea is to later on, patch those with static branches, so we don't incur
> any overhead when no mem cgroups with limited kmem are being used.
>
> Users of this functionality shall interact with the memcg core code
> through the following functions:
>
> memcg_kmem_newpage_charge: will return true if the group can handle the
> allocation. At this point, struct page is not
> yet allocated.
>
> memcg_kmem_commit_charge: will either revert the charge, if struct page
> allocation failed, or embed memcg information
> into page_cgroup.
>
> memcg_kmem_uncharge_page: called at free time, will revert the charge.
>
> ...
>
> +static __always_inline bool
> +memcg_kmem_newpage_charge(gfp_t gfp, struct mem_cgroup **memcg, int order)
> +{
> + if (!memcg_kmem_enabled())
> + return true;
> +
> + /*
> + * __GFP_NOFAIL allocations will move on even if charging is not
> + * possible. Therefore we don't even try, and have this allocation
> + * unaccounted. We could in theory charge it with
> + * res_counter_charge_nofail, but we hope those allocations are rare,
> + * and won't be worth the trouble.
> + */
> + if (!(gfp & __GFP_KMEMCG) || (gfp & __GFP_NOFAIL))
> + return true;
> + if (in_interrupt() || (!current->mm) || (current->flags & PF_KTHREAD))
> + return true;
> +
> + /* If the test is dying, just let it go. */
> + if (unlikely(test_thread_flag(TIF_MEMDIE)
> + || fatal_signal_pending(current)))
> + return true;
> +
> + return __memcg_kmem_newpage_charge(gfp, memcg, order);
> +}

That's a big function! Why was it __always_inline? I'd have thought
it would be better to move the code after memcg_kmem_enabled() out of
line.

Do we actually need to test PF_KTHREAD when current->mm == NULL?
Perhaps because of aio threads whcih temporarily adopt a userspace mm?

> +/**
> + * memcg_kmem_uncharge_page: uncharge pages from memcg
> + * @page: pointer to struct page being freed
> + * @order: allocation order.
> + *
> + * there is no need to specify memcg here, since it is embedded in page_cgroup
> + */
> +static __always_inline void
> +memcg_kmem_uncharge_page(struct page *page, int order)
> +{
> + if (memcg_kmem_enabled())
> + __memcg_kmem_uncharge_page(page, order);
> +}
> +
> +/**
> + * memcg_kmem_commit_charge: embeds correct memcg in a page
> + * @page: pointer to struct page recently allocated
> + * @memcg: the memcg structure we charged against
> + * @order: allocation order.
> + *
> + * Needs to be called after memcg_kmem_newpage_charge, regardless of success or
> + * failure of the allocation. if @page is NULL, this function will revert the
> + * charges. Otherwise, it will commit the memcg given by @memcg to the
> + * corresponding page_cgroup.
> + */
> +static __always_inline void
> +memcg_kmem_commit_charge(struct page *page, struct mem_cgroup *memcg, int order)
> +{
> + if (memcg_kmem_enabled() && memcg)
> + __memcg_kmem_commit_charge(page, memcg, order);
> +}

I suspect the __always_inline's here are to do with static branch
trickery. A code comment is warranted if so?

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[Message index]

		[PATCH v5 00/14] kmem controller for memcg. By: Glauber Costa on Tue, 16 October 2012 10:16
		[PATCH v5 03/14] memcg: change defines to an enum By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 03/14] memcg: change defines to an enum By: David Rientjes on Wed, 17 October 2012 21:50
		[PATCH v5 01/14] memcg: Make it possible to use the stock for more than one page. By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 01/14] memcg: Make it possible to use the stock for more than one page. By: akpm on Wed, 17 October 2012 22:11
		Re: [PATCH v5 01/14] memcg: Make it possible to use the stock for more than one page. By: Glauber Costa on Thu, 18 October 2012 08:55
		[PATCH v5 04/14] kmem accounting basic infrastructure By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: Michal Hocko on Tue, 16 October 2012 12:14
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: David Rientjes on Wed, 17 October 2012 22:08
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: Glauber Costa on Thu, 18 October 2012 09:02
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: Tejun Heo on Thu, 18 October 2012 19:47
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: Tejun Heo on Thu, 18 October 2012 19:37
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 04/14] kmem accounting basic infrastructure By: Glauber Costa on Thu, 18 October 2012 09:04
		[PATCH v5 11/14] memcg: allow a memcg with kmem charges to be destructed. By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 11/14] memcg: allow a memcg with kmem charges to be destructed. By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 11/14] memcg: allow a memcg with kmem charges to be destructed. By: Glauber Costa on Thu, 18 October 2012 09:33
		[PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: KAMEZAWA Hiroyuki on Wed, 17 October 2012 06:40
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Thu, 18 October 2012 09:16
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: David Rientjes on Thu, 18 October 2012 22:06
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Fri, 19 October 2012 09:10
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: David Rientjes on Fri, 19 October 2012 09:31
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Fri, 19 October 2012 10:00
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: David Rientjes on Wed, 17 October 2012 22:37
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Thu, 18 October 2012 09:23
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: David Rientjes on Thu, 18 October 2012 21:59
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Fri, 19 October 2012 10:08
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: David Rientjes on Fri, 19 October 2012 20:34
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Mon, 22 October 2012 12:34
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Michal Hocko on Mon, 22 October 2012 12:51
		Re: [PATCH v5 06/14] memcg: kmem controller infrastructure By: Glauber Costa on Mon, 22 October 2012 12:52
		[PATCH v5 05/14] Add a __GFP_KMEMCG flag By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 05/14] Add a __GFP_KMEMCG flag By: Michal Hocko on Tue, 16 October 2012 12:15
		Re: [PATCH v5 05/14] Add a __GFP_KMEMCG flag By: David Rientjes on Wed, 17 October 2012 22:09
		[PATCH v5 09/14] memcg: kmem accounting lifecycle management By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 09/14] memcg: kmem accounting lifecycle management By: David Rientjes on Wed, 17 October 2012 23:28
		Re: [PATCH v5 09/14] memcg: kmem accounting lifecycle management By: Michal Hocko on Thu, 18 October 2012 06:14
		Re: [PATCH v5 09/14] memcg: kmem accounting lifecycle management By: Glauber Costa on Thu, 18 October 2012 09:42
		[PATCH v5 10/14] memcg: use static branches when code not in use By: Glauber Costa on Tue, 16 October 2012 10:16
		[PATCH v5 14/14] Add documentation about the kmem controller By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: Michal Hocko on Tue, 16 October 2012 12:23
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: Christoph Lameter on Tue, 16 October 2012 18:25
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: Glauber Costa on Tue, 16 October 2012 19:02
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: Christoph Lameter on Tue, 16 October 2012 19:30
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 14/14] Add documentation about the kmem controller By: Glauber Costa on Thu, 18 October 2012 09:38
		[PATCH v5 13/14] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 13/14] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 13/14] protect architectures where THREAD_SIZE >= PAGE_SIZE against fork bombs By: Glauber Costa on Thu, 18 October 2012 09:37
		[PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: Glauber Costa on Tue, 16 October 2012 10:16
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: Christoph Lameter on Tue, 16 October 2012 15:31
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: Glauber Costa on Tue, 16 October 2012 18:55
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: akpm on Wed, 17 October 2012 22:12
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: Glauber Costa on Thu, 18 October 2012 09:24
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: akpm on Thu, 18 October 2012 20:44
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: Glauber Costa on Thu, 18 October 2012 11:53
		Re: [PATCH v5 07/14] mm: Allocate kernel pages to the right memcg By: David Rientjes on Wed, 17 October 2012 22:43
		Re: [PATCH v5 00/14] kmem controller for memcg. By: akpm on Wed, 17 October 2012 22:11
		Re: [PATCH v5 00/14] kmem controller for memcg. By: Glauber Costa on Thu, 18 October 2012 08:52
		Re: [PATCH v5 00/14] kmem controller for memcg. By: akpm on Thu, 18 October 2012 19:21
		Re: [PATCH v5 00/14] kmem controller for memcg. By: Glauber Costa on Fri, 19 October 2012 09:55

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