On Thu, Oct 28, 2021 at 8:16 PM Rafael J. Wysocki [off-list ref] wrote:

On Thu, Oct 28, 2021 at 7:57 PM Rafael J. Wysocki [off-list ref] wrote:

quoted

On Thu, Oct 28, 2021 at 7:29 PM Rafael J. Wysocki [off-list ref] wrote:

quoted

On Thu, Oct 28, 2021 at 7:10 PM Julia Lawall [off-list ref] wrote:

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Now, for your graph 3, are you saying this pseudo
code of the process is repeatable?:

Power up the system, booting kernel 5.9
switch to passive/schedutil.
wait X minutes for system to settle
do benchmark, result ~13 seconds
re-boot to kernel 5.15-RC
switch to passive/schedutil.
wait X minutes for system to settle
do benchmark, result ~40 seconds
re-boot to kernel 5.9
switch to passive/schedutil.
wait X minutes for system to settle
do benchmark, result ~28 seconds

In the first boot of 5.9, the des (desired?) field of the HWP_REQUEST
register is 0 and in the second boot (after booting 5.15 and entering
passive mode) it is 10.  I don't know though if this is a bug or a
feature...

I think I didn't understand you correctly, sorry about that.

In 5.15-rc (starting in 5.11-rc) the desired perf field in HWP_REQUEST
is used in the passive mode, so that is expected.

However, it may not be reset to 0 when going back from the passive to
the active mode.

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It looks like a bug.

I think that the desired value is not cleared on driver exit which
should happen.  Let me see if I can do a quick patch for that.

Please check the behavior with the attached patch applied.

Well, actually, the previous one won't do anything, because the
desired perf field is already cleared in this function before writing
the MSR, so please try the one attached to this message instead.

So with the last patch applied, can you please check if you get
desired=0 with 5.15-rc when switching driver modes from passive to
active?  FWIW, this works for me here.

In any case, the desired perf value in HWP_REQUEST is expected to be
reset to 0 on system restart.