Aboorva Devarajan [off-list ref] writes:

On Wed, 2023-09-13 at 08:54 +1000, Michael Ellerman wrote:

quoted

Aboorva Devarajan [off-list ref] writes:

quoted

From: Pratik R. Sampat <redacted>

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 <redacted>
Signed-off-by: Pratik R. Sampat <redacted>
Signed-off-by: Aboorva Devarajan <redacted>
---
 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 :)

cheers

Hi Michael,

Thanks a lot for taking a look at this.

Yes, this test-case can be used as a generic benchmark for evaluating
CPU idle latencies across different architectures, as it has thus far
been exclusively tested and used on PowerPC, so we thought it would be
more beneficial to incorporate it into a PowerPC specific self-test
suite. But I will work on making it a generic self-test and send across
a v4.

I'd suggest just posting v3 again but Cc'ing the cpuidle lists &
maintainers, to see if there is any interest in making it generic.

cheers