From: Roman Gushchin <guro@fb.com>
To: Christopher Lameter <cl@linux.com>
Cc: Waiman Long <longman@redhat.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
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-mm@kvack.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Shakeel Butt <shakeelb@goog>
Subject: Re: [PATCH 2/2] mm, slab: Extend vm/drop_caches to shrink kmem slabs
Date: Fri, 28 Jun 2019 16:33:41 +0000 [thread overview]
Message-ID: <20190628163334.GA3118@tower.DHCP.thefacebook.com> (raw)
In-Reply-To: <0100016b9eb7685e-0a5ab625-abb4-4e79-ab86-07744b1e4c3a-000000@email.amazonses.com>
On Fri, Jun 28, 2019 at 03:32:28PM +0000, Christopher Lameter wrote:
> On Thu, 27 Jun 2019, Roman Gushchin wrote:
>
> > so that objects belonging to different memory cgroups can share the same page
> > and kmem_caches.
> >
> > It's a fairly big change though.
>
> Could this be done at another level? Put a cgoup pointer into the
> corresponding structures and then go back to just a single kmen_cache for
> the system as a whole?
> You can still account them per cgroup and there
> will be no cleanup problem anymore. You could scan through a slab cache
> to remove the objects of a certain cgroup and then the fragmentation
> problem that cgroups create here will be handled by the slab allocators in
> the traditional way. The duplication of the kmem_cache was not designed
> into the allocators but bolted on later.
>
Yeah, this is exactly what I'm talking about. Idk how big the performance
penalty will be for small and short-living objects, it should be measured.
But for long-living objects it will be much better for sure...
Thanks!
WARNING: multiple messages have this Message-ID (diff)
From: Roman Gushchin <guro@fb.com>
To: Christopher Lameter <cl@linux.com>
Cc: Waiman Long <longman@redhat.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
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-mm@kvack.org>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Shakeel Butt <shakeelb@google.com>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH 2/2] mm, slab: Extend vm/drop_caches to shrink kmem slabs
Date: Fri, 28 Jun 2019 16:33:41 +0000 [thread overview]
Message-ID: <20190628163334.GA3118@tower.DHCP.thefacebook.com> (raw)
In-Reply-To: <0100016b9eb7685e-0a5ab625-abb4-4e79-ab86-07744b1e4c3a-000000@email.amazonses.com>
On Fri, Jun 28, 2019 at 03:32:28PM +0000, Christopher Lameter wrote:
> On Thu, 27 Jun 2019, Roman Gushchin wrote:
>
> > so that objects belonging to different memory cgroups can share the same page
> > and kmem_caches.
> >
> > It's a fairly big change though.
>
> Could this be done at another level? Put a cgoup pointer into the
> corresponding structures and then go back to just a single kmen_cache for
> the system as a whole?
> You can still account them per cgroup and there
> will be no cleanup problem anymore. You could scan through a slab cache
> to remove the objects of a certain cgroup and then the fragmentation
> problem that cgroups create here will be handled by the slab allocators in
> the traditional way. The duplication of the kmem_cache was not designed
> into the allocators but bolted on later.
>
Yeah, this is exactly what I'm talking about. Idk how big the performance
penalty will be for small and short-living objects, it should be measured.
But for long-living objects it will be much better for sure...
Thanks!
next prev parent reply other threads:[~2019-06-28 16:33 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 17:42 [PATCH 0/2] mm, slab: Extend vm/drop_caches to shrink kmem slabs Waiman Long
2019-06-24 17:42 ` [PATCH 1/2] mm, memcontrol: Add memcg_iterate_all() Waiman Long
2019-06-27 15:07 ` Michal Hocko
2019-06-27 21:03 ` Waiman Long
2019-06-28 7:10 ` Michal Hocko
2019-06-24 17:42 ` [PATCH 2/2] mm, slab: Extend vm/drop_caches to shrink kmem slabs Waiman Long
2019-06-26 20:19 ` Roman Gushchin
2019-06-26 20:19 ` Roman Gushchin
2019-06-27 20:57 ` Waiman Long
2019-06-27 20:57 ` Waiman Long
2019-06-27 21:24 ` Roman Gushchin
2019-06-27 21:24 ` Roman Gushchin
2019-06-27 21:31 ` Waiman Long
2019-06-27 21:31 ` Waiman Long
2019-06-28 15:32 ` Christopher Lameter
2019-06-28 15:32 ` Christopher Lameter
2019-06-28 16:33 ` Roman Gushchin [this message]
2019-06-28 16:33 ` Roman Gushchin
2019-06-28 17:16 ` Yang Shi
2019-06-28 17:16 ` Yang Shi
2019-06-28 17:30 ` Roman Gushchin
2019-06-28 17:30 ` Roman Gushchin
2019-06-27 21:25 ` Luis Chamberlain
2019-06-27 21:25 ` Luis Chamberlain
2019-06-27 15:15 ` Michal Hocko
2019-06-27 21:16 ` Waiman Long
2019-06-28 7:31 ` Michal Hocko
2019-07-02 18:41 ` Waiman Long
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