From: Suleiman Souhlal <suleiman@google.com>
To: Glauber Costa <glommer@parallels.com>
Cc: Suleiman Souhlal <ssouhlal@freebsd.org>,
cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com,
penberg@kernel.org, yinghan@google.com, hughd@google.com,
gthelen@google.com, linux-mm@kvack.org, devel@openvz.org
Subject: Re: [PATCH 07/10] memcg: Stop res_counter underflows.
Date: Tue, 28 Feb 2012 15:07:39 -0800 [thread overview]
Message-ID: <CABCjUKCaJVGShRKRkvBMrz_XNVGNrcguQ1uTP8Am1fQ1Te6PWA@mail.gmail.com> (raw)
In-Reply-To: <4F4CD731.60908@parallels.com>
On Tue, Feb 28, 2012 at 5:31 AM, Glauber Costa <glommer@parallels.com> wrote:
> I don't fully understand this.
> To me, the whole purpose of having a cache tied to a memcg, is that we know
> all allocations from that particular cache should be billed to a specific
> memcg. So after a cache is created, and has an assigned memcg,
> what's the point in bypassing it to root?
>
> It smells like you're just using this to circumvent something...
In the vast majority of the cases, we will be able to account to the cgroup.
However, there are cases when __mem_cgroup_try_charge() is not able to
do so, like when the task is being killed.
When this happens, the allocation will not get accounted to the
cgroup, but the slab accounting code will still think the page belongs
to the memcg's kmem_cache.
So, when we go to free the page, we assume that the page belongs to
the memcg and uncharge it, even though it was never charged to us in
the first place.
This is the situation this patch is trying to address, by keeping a
counter of how much memory has been bypassed like this, and uncharging
from the root if we have any outstanding bypassed memory.
Does that make sense?
-- Suleiman
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2012-02-28 23:07 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-27 22:58 [PATCH 00/10] memcg: Kernel Memory Accounting Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 01/10] memcg: Kernel memory accounting infrastructure Suleiman Souhlal
2012-02-28 13:10 ` Glauber Costa
2012-02-29 0:37 ` Suleiman Souhlal
2012-02-28 13:11 ` Glauber Costa
2012-02-27 22:58 ` [PATCH 02/10] memcg: Uncharge all kmem when deleting a cgroup Suleiman Souhlal
2012-02-28 19:00 ` Glauber Costa
2012-02-29 0:24 ` Suleiman Souhlal
2012-02-29 16:51 ` Glauber Costa
2012-02-29 6:22 ` KAMEZAWA Hiroyuki
2012-02-29 19:00 ` Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 03/10] memcg: Reclaim when more than one page needed Suleiman Souhlal
2012-02-29 6:18 ` KAMEZAWA Hiroyuki
2012-02-27 22:58 ` [PATCH 04/10] memcg: Introduce __GFP_NOACCOUNT Suleiman Souhlal
2012-02-29 6:00 ` KAMEZAWA Hiroyuki
2012-02-29 16:53 ` Glauber Costa
2012-02-29 19:09 ` Suleiman Souhlal
2012-03-01 0:10 ` KAMEZAWA Hiroyuki
2012-03-01 0:24 ` Glauber Costa
2012-03-01 6:05 ` KAMEZAWA Hiroyuki
2012-03-03 14:22 ` Glauber Costa
2012-03-03 16:38 ` Suleiman Souhlal
2012-03-03 23:24 ` Glauber Costa
2012-03-04 0:10 ` Suleiman Souhlal
2012-03-06 10:36 ` Glauber Costa
2012-03-06 16:13 ` Suleiman Souhlal
2012-03-06 18:31 ` Glauber Costa
2012-02-27 22:58 ` [PATCH 05/10] memcg: Slab accounting Suleiman Souhlal
2012-02-28 13:24 ` Glauber Costa
2012-02-28 23:31 ` Suleiman Souhlal
2012-02-29 17:00 ` Glauber Costa
2012-02-27 22:58 ` [PATCH 06/10] memcg: Track all the memcg children of a kmem_cache Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 07/10] memcg: Stop res_counter underflows Suleiman Souhlal
2012-02-28 13:31 ` Glauber Costa
2012-02-28 23:07 ` Suleiman Souhlal [this message]
2012-02-29 17:05 ` Glauber Costa
2012-02-29 19:17 ` Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 08/10] memcg: Add CONFIG_CGROUP_MEM_RES_CTLR_KMEM_ACCT_ROOT Suleiman Souhlal
2012-02-28 13:34 ` Glauber Costa
2012-02-28 23:36 ` Suleiman Souhlal
2012-02-28 23:54 ` KAMEZAWA Hiroyuki
2012-02-29 17:09 ` Glauber Costa
2012-02-29 19:24 ` Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 09/10] memcg: Per-memcg memory.kmem.slabinfo file Suleiman Souhlal
2012-02-27 22:58 ` [PATCH 10/10] memcg: Document kernel memory accounting Suleiman Souhlal
2012-02-27 23:05 ` Randy Dunlap
2012-02-28 8:49 ` [PATCH 00/10] memcg: Kernel Memory Accounting Pekka Enberg
2012-02-28 22:12 ` Suleiman Souhlal
2012-02-28 13:03 ` Glauber Costa
2012-02-28 22:47 ` Suleiman Souhlal
2012-02-29 16:47 ` Glauber Costa
2012-02-29 19:28 ` Suleiman Souhlal
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CABCjUKCaJVGShRKRkvBMrz_XNVGNrcguQ1uTP8Am1fQ1Te6PWA@mail.gmail.com \
--to=suleiman@google.com \
--cc=cgroups@vger.kernel.org \
--cc=devel@openvz.org \
--cc=glommer@parallels.com \
--cc=gthelen@google.com \
--cc=hughd@google.com \
--cc=kamezawa.hiroyu@jp.fujitsu.com \
--cc=linux-mm@kvack.org \
--cc=penberg@kernel.org \
--cc=ssouhlal@freebsd.org \
--cc=yinghan@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox