Messages in this thread | | | From | Valentin Schneider <> | Subject | Re: 5.11-rc4+git: Shortest NUMA path spans too many nodes | Date | Thu, 21 Jan 2021 15:05:32 +0000 |
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(+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.
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