[RFC v3 1/2] powerpc/cpuidle: cpuidle wakeup latency based on IPI and timer events

Michael Ellerman mpe at ellerman.id.au
Wed Sep 13 08:54:15 AEST 2023

Aboorva Devarajan <aboorvad at linux.vnet.ibm.com> writes:
> From: Pratik R. Sampat <psampat at linux.ibm.com>
> Introduce a mechanism to fire directed IPIs from a source CPU to a
> specified target CPU and measure the time incurred on waking up the
> target CPU in response.
> Also, introduce a mechanism to queue a hrtimer on a specified CPU and
> subsequently measure the time taken to wakeup the CPU.
> Define a simple debugfs interface that allows for adjusting the
> settings to trigger IPI and timer events on a designated CPU, and to
> observe the resulting cpuidle wakeup latencies.
> Reviewed-by: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
> Signed-off-by: Pratik R. Sampat <psampat at linux.ibm.com>
> Signed-off-by: Aboorva Devarajan <aboorvad at linux.vnet.ibm.com>
> ---
>  arch/powerpc/Kconfig.debug                 |  10 ++
>  arch/powerpc/kernel/Makefile               |   1 +
>  arch/powerpc/kernel/test_cpuidle_latency.c | 154 +++++++++++++++++++++
I don't see anything here that's powerpc specific?

Which makes me wonder 1) could this be done with some existing generic
mechanism?, and 2) if not can this test code be made generic.

At the very least this should be Cc'ed to the cpuidle lists &
maintainers given it's a test for cpuidle latency :)


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