From: Valentin Schneider <valentin.schneider@arm.com>
To: Meelis Roos <mroos@linux.ee>, LKML <linux-kernel@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Barry Song <song.bao.hua@hisilicon.com>,
Mel Gorman <mgorman@suse.de>,
Dietmar Eggemann <dietmar.eggemann@arm.com>
Subject: Re: 5.11-rc4+git: Shortest NUMA path spans too many nodes
Date: Thu, 21 Jan 2021 15:05:32 +0000 [thread overview]
Message-ID: <jhjmtx22uv7.mognet@arm.com> (raw)
In-Reply-To: <3ec17983-7959-eccd-af25-400056a5877d@linux.ee>
(+Cc relevant folks)
Hi,
On 21/01/21 15:41, Meelis Roos wrote:
> This happens on Sun Fire X4600 M2 - 32 cores in 8 CPU slots. 5.10 was silent. Current git and
> 5.10.0-13256-g5814bc2d4cc2 exhibit this message in dmesg but otherwise seem to work fine
> (kernel compilation succeeds).
>
b5b217346de8 ("sched/topology: Warn when NUMA diameter > 2") was added in
5.11-rc1, and I believe was marked for stable.
It doesn't come with a scheduler behaviour change, it only catches
topologies that end up being silently (unless run with SCHED_DEBUG=y)
misrepresented / misinterpreted by the scheduler.
Up until now I had only seen it fire on a single, somewhat unusual
topology. As fixing it is far from trivial, I figured adding this warning
would let us build a case for actually fixing it if we get some more
reports.
Could you paste the output of the below?
$ cat /sys/devices/system/node/node*/distance
Additionally, booting your system with CONFIG_SCHED_DEBUG=y and
appending 'sched_debug' to your cmdline should yield some extra data.
next prev parent reply other threads:[~2021-01-21 15:09 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 13:41 5.11-rc4+git: Shortest NUMA path spans too many nodes Meelis Roos
2021-01-21 15:05 ` Valentin Schneider [this message]
2021-01-21 17:39 ` Meelis Roos
2021-01-21 18:21 ` Valentin Schneider
2021-01-21 18:53 ` Dietmar Eggemann
2021-01-21 21:17 ` Song Bao Hua (Barry Song)
2021-01-22 10:05 ` Dietmar Eggemann
2021-01-22 11:09 ` Song Bao Hua (Barry Song)
2021-01-22 11:16 ` Valentin Schneider
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