linux-kernel - Re: cpufreq governors broken with !CONFIG

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Message-ID: <1961527.dEtpL4HAvs@vostro.rjw.lan>
Date:	Fri, 06 May 2016 02:09:07 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Steve Muckle <steve.muckle@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: cpufreq governors broken with !CONFIG_SMP?

On Thursday, May 05, 2016 04:49:22 PM Steve Muckle wrote:
> While working on a few patches for schedutil I noticed that the CFS
> cpufreq hooks depend on PELT, which depends on CONFIG_SMP.
> 
> I compiled and ran a UP kernel with intel_pstate. Running a cpu-bound
> task did not result in the frequency increasing beyond fmin. For some reason
> ondemand is working for me with the same test, not sure why yet.
> 
> It appears dbs/intel-pstate/schedutil have a dependency on CONFIG_SMP
> now. Or am I missing something?

You're right AFAICS.

For governors other than schedutil fixing that would be a matter of
adding a !CONFIG_SMP variant of update_load_avg() that will call
cpufreq_update_util() and do nothing else.  It doesn't matter what
is passed via util and max then.

In turn, schedutil should probably depend on CONFIG_SMP.

Peter?