linux-kernel - Re: [PATCH v4 0/2] cpufreq: intel_pstate: Implement passive mode with HWP enabled

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Date:   Sat, 01 Aug 2020 09:39:30 -0700
From:   Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>
Cc:     Linux Documentation <linux-doc@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Doug Smythies <dsmythies@...us.net>,
        Francisco Jerez <francisco.jerez.plata@...el.com>
Subject: Re: [PATCH v4 0/2] cpufreq: intel_pstate: Implement passive mode
 with HWP enabled

On Tue, 2020-07-28 at 17:09 +0200, Rafael J. Wysocki wrote:
> Hi All,
> 
> On Monday, July 27, 2020 5:13:40 PM CEST Rafael J. Wysocki wrote:
> > On Thursday, July 16, 2020 7:37:04 PM CEST Rafael J. Wysocki wrote:
> > > This really is a v2 of this patch:
> > > 
> > > https://patchwork.kernel.org/patch/11663271/
> > > 
> > > with an extra preceding cleanup patch to avoid making unrelated
> > > changes in the
> > > [2/2].
> > 
I applied this series along with
[PATCH] cpufreq: intel_pstate: Fix EPP setting via sysfs in active mode
on 5.8 latest master (On top of raw epp patchset).

When intel_pstate=passive from kernel command line then it is fine, no
crash. But switch dynamically, crashed:
Attached crash.txt. I may need to try your linux-pm tree.

Then after some playing I reached a state when I monitor MSR 0x774:
while true; do rdmsr 0x774; sleep 1; done
80002704
...
...
ff000101
ff000101
ff000101
ff000101
ff000101
ff000101
ff000101
ff000101

Don't have a recipe to reproduce this.

Thanks,
Srinivas

> > Almost the same as before, but the first patch has been reworked to
> > handle
> > errors in store_energy_performance_preference() correctly and
> > rebased on top
> > of the current linux-pm.git branch.
> > 
> > No functional changes otherwise.
> 
> One more update of the second patch.
> 
> Namely, I realized that the hwp_dynamic_boost sysfs switch was
> present in the
> passive mode after the v3 (and the previous versions) of that patch
> which isn't
> correct, so this modifies it to avoid exposing hwp_dynamic_boost in
> the passive
> mode.
> 
> The first patch is the same as in the v2.
> 
> Thanks!
> 
> 
> 

View attachment "crash.txt" of type "text/plain" (5520 bytes)