From: Waiman Long <longman@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
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: Wed, 3 Jul 2019 11:21:16 -0400 [thread overview]
Message-ID: <c29ff725-95ba-db4d-944f-d33f5f766cd3@redhat.com> (raw)
In-Reply-To: <20190702143340.715f771192721f60de1699d7@linux-foundation.org>
On 7/2/19 5:33 PM, Andrew Morton wrote:
> On Tue, 2 Jul 2019 16:44:24 -0400 Waiman Long <longman@redhat.com> wrote:
>
>> On 7/2/19 4:03 PM, Andrew Morton wrote:
>>> 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.
>> Sure. Essentially, the sysfs shrink interface is not complete. It allows
>> the root cache to be shrunk, but not any of the memcg caches.
> But that doesn't describe anything of value. Who wants to use this,
> and why? How will it be used? What are the use-cases?
>
For me, the primary motivation of posting this patch is to have a way to
make the number of active objects reported in /proc/slabinfo more
accurately reflect the number of objects that are actually being used by
the kernel. When measuring changes in slab objects consumption between
successive run of a certain workload, I can more easily see the amount
of increase. Without that, the data will have much more noise and it
will be harder to see a pattern.
Cheers,
Longman
next prev parent reply other threads:[~2019-07-03 15:21 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
2019-07-02 20:44 ` Waiman Long
2019-07-02 21:33 ` Andrew Morton
2019-07-03 15:21 ` Waiman Long [this message]
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
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