linux-kernel - Re: [PATCH] Revert "cpuidle: Replace ktime_get() with local

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Date:   Thu, 20 Apr 2017 15:49:22 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Ville Syrjälä <ville.syrjala@...ux.intel.com>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Daniel Lezcano <daniel.lezcano@...aro.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH] Revert "cpuidle: Replace ktime_get() with local_clock()"

On Thu, Apr 20, 2017 at 04:43:45PM +0300, Ville Syrjälä wrote:
> On Thu, Apr 20, 2017 at 03:08:13PM +0200, Peter Zijlstra wrote:
> > On Thu, Apr 20, 2017 at 03:44:47PM +0300, ville.syrjala@...ux.intel.com wrote:
> > > From: Ville Syrjälä <ville.syrjala@...ux.intel.com>
> > > 
> > > This reverts commit e93e59ce5b85e6c2b444f09fd1f707274ec066dc.
> > > 
> > > The TSC stops in deeper C states, 
> > 
> > On some old hardware (Core2 era and before) only. You've forgotten to
> > mention what hardware you've observed problems with.
> 
> Yeah, Core2 is what I used when I finally decided to bisect this. I've
> been plagued by the bogus powertop numbers on many machines, most
> likely all of them were of some older vintage.

> Tested-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>

OK, thanks. I'm currently chasing some other Core2 issue that is
somewhat related. See:

  http://lkml.kernel.org/r/20170413132349.thxkwptdymsfsyxb@hirez.programming.kicks-ass.net

Once I have that sorted I'll post both patches.