From: Vlastimil Babka <vbabka@suse.cz>
To: Roman Gushchin <guro@fb.com>
Cc: akpm@linux-foundation.org, bigeasy@linutronix.de, cl@linux.com,
hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, jannh@google.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
mhocko@kernel.org, minchan@kernel.org, penberg@kernel.org,
rientjes@google.com, shakeelb@google.com, surenb@google.com,
tglx@linutronix.de
Subject: Re: [RFC 2/2] mm, slub: add shrinker to reclaim cached slabs
Date: Tue, 26 Jan 2021 13:06:35 +0100 [thread overview]
Message-ID: <51de513a-9c4e-35fa-fd04-977480ac50a0@suse.cz> (raw)
In-Reply-To: <20210122004847.GA25567@carbon.dhcp.thefacebook.com>
On 1/22/21 1:48 AM, Roman Gushchin wrote:
> On Thu, Jan 21, 2021 at 06:21:54PM +0100, Vlastimil Babka wrote:
>
> Hi Vlastimil!
>
> This makes a lot of sense, however it looks a bit as an overkill to me (on 5.9+).
> Isn't limiting a number of pages (instead of number of objects) sufficient on 5.9+?
It would help, but fundamentally there can still be a lot of memory locked up
with e.g. many CPU's. We should have a way to flush this automatically, like for
other cached things.
> If not, maybe we can limit the shrinking to the pre-OOM condition?
> Do we really need to trip it constantly?
The priority could be reduced, pre-OOM might be too extreme. Why reclaim e.g.
actually used LRU pages instead of unused slab pages?
IMHO a frequently reclaiming system probably doesn't benefit from SLUB's peak
performance at that point anyway...
> Thanks!
>
prev parent reply other threads:[~2021-01-26 12:06 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-11 23:12 SLUB: percpu partial object count is highly inaccurate, causing some memory wastage and maybe also worse tail latencies? Jann Horn
2021-01-12 0:27 ` Roman Gushchin
2021-01-12 16:35 ` Christoph Lameter
2021-01-14 9:27 ` Vlastimil Babka
2021-01-18 11:03 ` Michal Hocko
2021-01-18 15:46 ` Christoph Lameter
2021-01-18 16:07 ` Michal Hocko
2021-01-13 19:14 ` Vlastimil Babka
2021-01-13 22:37 ` Jann Horn
2021-01-14 9:04 ` Christoph Lameter
2021-01-21 17:21 ` Vlastimil Babka
2021-01-21 17:21 ` [RFC 1/2] mm, vmscan: add priority field to struct shrink_control Vlastimil Babka
2021-01-21 17:21 ` [RFC 2/2] mm, slub: add shrinker to reclaim cached slabs Vlastimil Babka
2021-01-22 0:48 ` Roman Gushchin
2021-01-26 12:06 ` Vlastimil Babka [this message]
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