sched/cputime: Handle dyntick-idle steal time correctly

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The dyntick-idle steal time is currently accounted when the tick restarts
but the stolen idle time is not subtracted from the idle time that was
already accounted. This is to avoid observing the idle time going backward
as the dyntick-idle cputime accessors can't reliably know in advance the
stolen idle time.

In order to maintain a forward progressing idle cputime while subtracting
idle steal time from it, keep track of the previously accounted idle stolen
time and substract it from _later_ idle cputime accounting.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Link: https://patch.msgid.link/20260508131647.43868-16-frederic@kernel.org

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Frederic Weisbecker 2026-05-08 15:16:47 +02:00 • committed by Thomas Gleixner

parent 7198e3927a

commit 6199f9999a

2 changed files with 24 additions and 5 deletions

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1

include/linux/kernel_stat.h

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28

kernel/sched/cputime.c

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