From: Mel Gorman <mgorman@techsingularity.net>
To: Doug Smythies <dsmythies@telus.net>
Cc: "'Rafael J. Wysocki'" <rafael@kernel.org>,
'Rafael Wysocki' <rjw@rjwysocki.net>,
'Ingo Molnar' <mingo@kernel.org>,
'Peter Zijlstra' <peterz@infradead.org>,
'Matt Fleming' <matt@codeblueprint.co.uk>,
'Mike Galbraith' <umgwanakikbuti@gmail.com>,
'Linux-PM' <linux-pm@vger.kernel.org>,
'LKML' <linux-kernel@vger.kernel.org>,
'Srinivas Pandruvada' <srinivas.pandruvada@linux.intel.com>
Subject: Re: [PATCH 1/1] intel_pstate: Increase hold-off time before busyness is scaled
Date: Tue, 23 Feb 2016 14:04:59 +0000 [thread overview]
Message-ID: <20160223140459.GA2854@techsingularity.net> (raw)
In-Reply-To: <001101d16a90$a7a26e10$f6e74a30$@net>
On Thu, Feb 18, 2016 at 01:09:26PM -0800, Doug Smythies wrote:
> >> +++ b/drivers/cpufreq/intel_pstate.c
> >> @@ -999,7 +999,7 @@ static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
> >> sample_time = pid_params.sample_rate_ms * USEC_PER_MSEC;
> >> duration_us = ktime_us_delta(cpu->sample.time,
> >> cpu->last_sample_time);
> >> - if (duration_us > sample_time * 3) {
> >> + if (duration_us > sample_time * 12) {
> >> sample_ratio = div_fp(int_tofp(sample_time),
> >> int_tofp(duration_us));
> >> core_busy = mul_fp(core_busy, sample_ratio);
> >> --
>
> The immediately preceding comment needs to be changed also.
> Note that with duration related scaling only coming in at such a high
> ratio it might be worth saving the divide and just setting it to 0.
>
I tried this and FWIW, the performance is generally comparable as is the
power usage as reported by turbostat. On occasion, depending on the
machine, the system CPU usage is noticably lower.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2016-02-23 14:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-18 11:11 [PATCH 1/1] intel_pstate: Increase hold-off time before busyness is scaled Mel Gorman
2016-02-18 19:43 ` Rafael J. Wysocki
2016-02-18 21:09 ` Doug Smythies
2016-02-19 10:49 ` Mel Gorman
2016-02-23 14:04 ` Mel Gorman [this message]
2016-02-18 23:29 ` Pandruvada, Srinivas
2016-02-18 23:33 ` Rafael J. Wysocki
2016-02-19 11:11 ` Stephane Gasparini
2016-02-19 16:38 ` Doug Smythies
2016-02-24 16:19 ` Stephane Gasparini
2016-02-25 19:51 ` Doug Smythies
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