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From: "Doug Smythies" <dsmythies@telus.net>
To: 'Srinivas Pandruvada' <srinivas.pandruvada@linux.intel.com>
Cc: "'Rafael J. Wysocki'" <rjw@rjwysocki.net>,
	'Philippe Longepe' <philippe.longepe@linux.intel.com>,
	linux-pm@vger.kernel.org, 'Len Brown' <len.brown@intel.com>,
	"'Rafael J. Wysocki'" <rafael@kernel.org>,
	'Stephane Gasparini' <stephane.gasparini@linux.intel.com>
Subject: RE: [PATCH V4] intel_pstate: Use avg_pstate instead of current_pstate
Date: Fri, 22 Apr 2016 08:18:49 -0700	[thread overview]
Message-ID: <004701d19caa$4644c360$d2ce4a20$@net> (raw)
In-Reply-To: <CAJZ5v0hMTanSQQ9VX2YbTgRvtUkkTDJAJSYcHGxAdtm=xEHE6g@mail.gmail.com>

Srinivas,

Recall a couple of months ago, on the "Increase hold-off time before busyness is scaled"
thread, Stephane suggested we try applying this method on the get_target_pstate_use_performance
branch of the intel_pstate driver, as opposed to just on the get_target_pstate_use_cpu_load branch.

It didn't make any difference with respect to the hold-off time issue.
However, I did spend considerable time testing it in other scenarios.
It does somewhat temper the occasional tendency to suddenly have a ridiculously high
scaled busy number with virtually no load (the same issue from the
"[intel-pstate driver regression] processor frequency very high even if in idle" thread,
that continued in https://bugzilla.kernel.org/show_bug.cgi?id=115771 )
I didn't find any significant regression, and did observe some small energy savings
in some scenarios (admittedly, small enough to have possibly been simply test to test
variations, and I didn't do enough tests to extract a definite trend).

I am suggesting to consider extending the patch to get_target_pstate_use_performance also.

... Doug



  reply	other threads:[~2016-04-22 15:18 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-04  7:23 [PATCH V4] intel_pstate: Use avg_pstate instead of current_pstate Philippe Longepe
2016-04-04  7:23 ` Philippe Longepe
2016-04-22  0:48 ` Rafael J. Wysocki
2016-04-22  0:59   ` Srinivas Pandruvada
2016-04-22  1:01     ` Rafael J. Wysocki
2016-04-22 15:18       ` Doug Smythies [this message]
2016-04-22 16:26         ` Srinivas Pandruvada

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