Messages in this thread | | | Date | Wed, 22 Nov 2023 06:43:24 +0700 | From | Bagas Sanjaya <> | Subject | Re: [REGRESSION] Perf (userspace) broken on big.LITTLE systems since v6.5 |
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On Tue, Nov 21, 2023 at 09:08:48PM +0900, Hector Martin wrote: > Perf broke on all Apple ARM64 systems (tested almost everything), and > according to maz also on Juno (so, probably all big.LITTLE) since v6.5. > > Test command: > > sudo taskset -c 0 ./perf stat -e apple_icestorm_pmu/cycles/ -e > apple_firestorm_pmu/cycles/ -e cycles ls > > Since this is taskset to CPU #0 (LITTLE core, icestorm), only events for > icestorm are expected. > > I bisected the breakage to two distinct points: > > 5ea8f2ccffb is the first bad commit. With its parent, the output is as > expected (same as v6.4): > > 3,297,462 apple_icestorm_pmu/cycles/ > > <not counted> apple_firestorm_pmu/cycles/ > (0.00%) > <not counted> cycles > (0.00%) > > With 5ea8f2ccffb everything breaks: > > <not supported> apple_icestorm_pmu/cycles/ > > <not supported> apple_firestorm_pmu/cycles/ > > <not counted> cycles > (0.00%) > > Somewhere along the way to 82fe2e45cdb00 things get even worse (didn't > bother bisecting this range). With its parent: > > <not supported> apple_icestorm_pmu/cycles/ > > <not supported> apple_firestorm_pmu/cycles/ > > <not supported> apple_icestorm_pmu/cycles/ > > <not supported> apple_firestorm_pmu/cycles/ > > Then 82fe2e45cdb00 leads to the current v6.5 behavior: > > <not counted> apple_icestorm_pmu/cycles/ > (0.00%) > <not counted> apple_firestorm_pmu/cycles/ > (0.00%) > <not counted> cycles > (0.00%) > > If I taskset the task to CPU#2 (big core, firestorm), I get events: > > 1,454,858 apple_icestorm_pmu/cycles/ > > 1,454,760 apple_firestorm_pmu/cycles/ > > 1,454,384 cycles > > > So the current behavior is that all output seems to come from the > firestorm PMU event counter, regardless of requested event. > > This is all unchanged and still broken in v6.7-rc2. >
Thanks for the regression report (and it has been handled well already). I'm adding it to regzbot for tracking:
#regzbot ^introduced: 5ea8f2ccffb239
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