Gautham R. Shenoy e6601bb3cb pm: cpupower: Fix the snapshot-order of tsc,mperf, clock in mperf_stop() ...

[ Upstream commit cda7ac8ce7 ]

In the function mperf_start(), mperf_monitor snapshots the time, tsc
and finally the aperf,mperf MSRs. However, this order of snapshotting
in is reversed in mperf_stop(). As a result, the C0 residency (which
is computed as delta_mperf * 100 / delta_tsc) is under-reported on
CPUs that is 100% busy.

Fix this by snapshotting time, tsc and then aperf,mperf in
mperf_stop() in the same order as in mperf_start().

Link: https://lore.kernel.org/r/20250612122355.19629-2-gautham.shenoy@amd.com
Signed-off-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2025-08-20 18:30:27 +02:00

..

amd_fam14h_idle.c

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cpuidle_sysfs.c

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cpupower-monitor.c

cpupower: Change the var type of the 'monitor' subcommand display mode

2024-06-20 10:08:08 -06:00

cpupower-monitor.h

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hsw_ext_idle.c

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idle_monitors.def

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idle_monitors.h

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mperf_monitor.c

pm: cpupower: Fix the snapshot-order of tsc,mperf, clock in mperf_stop()

2025-08-20 18:30:27 +02:00

nhm_idle.c

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rapl_monitor.c

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snb_idle.c

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