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SubjectRe: [PATCH] Restore deterministic CPU accounting on powerpc

* Paul Mackerras <> wrote:

> Since powerpc started using CONFIG_GENERIC_CLOCKEVENTS, the
> deterministic CPU accounting (CONFIG_VIRT_CPU_ACCOUNTING) has been
> broken on powerpc, because we end up counting user time twice: once in
> timer_interrupt() and once in update_process_times().
> This fixes the problem by pulling the code in update_process_times
> that updates utime and stime into a separate function called
> account_process_tick. If CONFIG_VIRT_CPU_ACCOUNTING is not defined,
> there is a version of account_process_tick in kernel/timer.c that
> simply accounts a whole tick to either utime or stime as before. If
> CONFIG_VIRT_CPU_ACCOUNTING is defined, then arch code gets to
> implement account_process_tick.
> This also lets us simplify the s390 code a bit; it means that the s390
> timer interrupt can now call update_process_times even when
> CONFIG_VIRT_CPU_ACCOUNTING is turned on, and can just implement a
> suitable account_process_tick().
> Signed-off-by: Paul Mackerras <>

lets push this towards Linus via the scheduler tree, ok?

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