linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andrew Morton <akpm@linux-foundation.org>
To: Waiman Long <longman@redhat.com>
Cc: Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Jonathan Corbet <corbet@lwn.net>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	linux-mm@kvack.org, linux-doc@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org,
	linux-kernel@vger.kernel.org, Roman Gushchin <guro@fb.com>,
	Shakeel Butt <shakeelb@google.com>,
	Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches
Date: Tue, 2 Jul 2019 13:03:18 -0700	[thread overview]
Message-ID: <20190702130318.39d187dc27dbdd9267788165@linux-foundation.org> (raw)
In-Reply-To: <20190702183730.14461-1-longman@redhat.com>

On Tue,  2 Jul 2019 14:37:30 -0400 Waiman Long <longman@redhat.com> wrote:

> Currently, a value of '1" is written to /sys/kernel/slab/<slab>/shrink
> file to shrink the slab by flushing all the per-cpu slabs and free
> slabs in partial lists. This applies only to the root caches, though.
> 
> Extends this capability by shrinking all the child memcg caches and
> the root cache when a value of '2' is written to the shrink sysfs file.

Why?

Please fully describe the value of the proposed feature to or users. 
Always.

> 
> ...
>
> --- a/Documentation/ABI/testing/sysfs-kernel-slab
> +++ b/Documentation/ABI/testing/sysfs-kernel-slab
> @@ -429,10 +429,12 @@ KernelVersion:	2.6.22
>  Contact:	Pekka Enberg <penberg@cs.helsinki.fi>,
>  		Christoph Lameter <cl@linux-foundation.org>
>  Description:
> -		The shrink file is written when memory should be reclaimed from
> -		a cache.  Empty partial slabs are freed and the partial list is
> -		sorted so the slabs with the fewest available objects are used
> -		first.
> +		A value of '1' is written to the shrink file when memory should
> +		be reclaimed from a cache.  Empty partial slabs are freed and
> +		the partial list is sorted so the slabs with the fewest
> +		available objects are used first.  When a value of '2' is
> +		written, all the corresponding child memory cgroup caches
> +		should be shrunk as well.  All other values are invalid.

One would expect this to be a bitfield, like /proc/sys/vm/drop_caches. 
So writing 3 does both forms of shrinking.

Yes, it happens to be the case that 2 is a superset of 1, but what
about if we add "4"?


  parent reply	other threads:[~2019-07-03  0:53 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-02 18:37 [PATCH] mm, slab: Extend slab/shrink to shrink all the memcg caches Waiman Long
2019-07-02 18:39 ` Waiman Long
2019-07-02 19:09 ` David Rientjes
2019-07-02 19:15   ` Waiman Long
2019-07-02 19:30 ` Roman Gushchin
2019-07-02 20:03 ` Andrew Morton [this message]
2019-07-02 20:44   ` Waiman Long
2019-07-02 21:33     ` Andrew Morton
2019-07-03 15:21       ` Waiman Long
2019-07-03 15:53         ` Michal Hocko
2019-07-03 16:16           ` Waiman Long
2019-07-04  7:37             ` Michal Hocko
2019-07-03  6:56 ` Michal Hocko
2019-07-03 13:12   ` Waiman Long
2019-07-03 14:37     ` Michal Hocko
2019-07-03 15:14       ` Waiman Long
2019-07-03 16:10     ` Christopher Lameter
2019-07-03 16:13       ` Waiman Long
2019-07-22 12:46 ` peter enderborg
2019-07-23 14:30   ` Waiman Long
2019-08-07 16:33     ` Vlastimil Babka

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=20190702130318.39d187dc27dbdd9267788165@linux-foundation.org \
    --to=akpm@linux-foundation.org \
    --cc=aarcange@redhat.com \
    --cc=cgroups@vger.kernel.org \
    --cc=cl@linux.com \
    --cc=corbet@lwn.net \
    --cc=guro@fb.com \
    --cc=hannes@cmpxchg.org \
    --cc=iamjoonsoo.kim@lge.com \
    --cc=keescook@chromium.org \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=longman@redhat.com \
    --cc=mcgrof@kernel.org \
    --cc=mhocko@kernel.org \
    --cc=penberg@kernel.org \
    --cc=rientjes@google.com \
    --cc=shakeelb@google.com \
    --cc=vdavydov.dev@gmail.com \
    --cc=viro@zeniv.linux.org.uk \
    /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;
as well as URLs for NNTP newsgroup(s).