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From: Vlastimil Babka <vbabka@suse.cz>
To: Christoph Lameter <cl@linux.com>, Jann Horn <jannh@google.com>
Cc: Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	kernel list <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Roman Gushchin <guro@fb.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>,
	Suren Baghdasaryan <surenb@google.com>,
	Minchan Kim <minchan@kernel.org>,
	Michal Hocko <mhocko@kernel.org>
Subject: SLUB: percpu partial object count is highly inaccurate, causing some memory wastage and maybe also worse tail latencies?
Date: Thu, 14 Jan 2021 10:27:40 +0100	[thread overview]
Message-ID: <e4d89d4f-62d4-43e3-9dd7-2496e955b437@suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2101121627490.20570@www.lameter.com>

On 1/12/21 5:35 PM, Christoph Lameter wrote:
> On Tue, 12 Jan 2021, Jann Horn wrote:
> 
>> [This is not something I intend to work on myself. But since I
>> stumbled over this issue, I figured I should at least document/report
>> it, in case anyone is willing to pick it up.]
> 
> Well yeah all true. There is however a slabinfo tool that has an -s option
> to shrink all slabs.
> 
> 	slabinfo -s
> 
> So you could put that somewhere that executes if the system is
> idle or put it into cron or so.

Hm this would be similar to recommending a periodical echo > drop_caches
operation. We actually discourage from that (and yeah, some tools do that, and
we now report those in dmesg). I believe the kernel should respond to memory
pressure and not OOM prematurely by itself, including SLUB.


  reply	other threads:[~2021-01-14  9:27 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 [this message]
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

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