From: Christoph Lameter <cl@linux.com>
To: 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>
Subject: Re: SLUB: percpu partial object count is highly inaccurate, causing some memory wastage and maybe also worse tail latencies?
Date: Tue, 12 Jan 2021 16:35:28 +0000 (UTC) [thread overview]
Message-ID: <alpine.DEB.2.22.394.2101121627490.20570@www.lameter.com> (raw)
In-Reply-To: <CAG48ez2Qx5K1Cab-m8BdSibp6wLTip6ro4=-umR7BLsEgjEYzA@mail.gmail.com>
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.
This is a heavy handed operation through. You could switch off partial cpu
slabs completely to avoid the issue. Nothing came to mind in the past on
how to solve this without sacrificing significant performance or cause
some system processing at random times while the shrinking runs. No one
wants any of that.
Being able to do it from userspace cleanly shifts the burden to userspace ;-)
You can even do random heavy system processing from user space if you put
a sleep there for random seconds between the shrinking runs.
next prev parent reply other threads:[~2021-01-12 16:35 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 [this message]
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
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=alpine.DEB.2.22.394.2101121627490.20570@www.lameter.com \
--to=cl@linux.com \
--cc=akpm@linux-foundation.org \
--cc=bigeasy@linutronix.de \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=jannh@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=minchan@kernel.org \
--cc=penberg@kernel.org \
--cc=rientjes@google.com \
--cc=shakeelb@google.com \
--cc=surenb@google.com \
--cc=tglx@linutronix.de \
/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).