Quoting Giovanni Gherdovich (2020-03-31 19:11:25) > Hello Chris, > > thank you for catching this problem and sorry for the mess. > > Until your message I wasn't aware that CPU0 can be hotplugged, but now that I > check the feature is been there since v3.8 :/ > > The code assumes cpu0 is always there and I need to fix that. > > It seems your report comes from executing an automated test suite, can you > give me a link to the test sources and a hint on how to run it? I'd like to > reproduce locally so that I make sure I correctly address this problem. https://gitlab.freedesktop.org/drm/igt-gpu-tools/ It's an i915 test (so expects i915 running and root access to your machine, with the intent of breaking your machine), but the cpu hotplugging could be extracted https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/blob/master/tests/perf_pmu.c#L1153 since it's basically doing: i = 0 while :; do test -e /sys/devices/system/cpu/cpu$i/online || break echo 0 > /sys/devices/system/cpu/cpu$i/online sleep .1 echo 1 > /sys/devices/system/cpu/cpu$i/online i = $[[ $i + 1 ]] done dmesg Possibly running that under perf stat to keep perf_event_open, or something else that hooks up the perf cpu hotplug callbacks. Hope that helps, -Chris
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