From: "Doug Smythies" <dsmythies@telus.net>
To: "'Rafael J. Wysocki'" <rjw@rjwysocki.net>,
"'Linux PM'" <linux-pm@vger.kernel.org>
Cc: "'Srinivas Pandruvada'" <srinivas.pandruvada@linux.intel.com>,
"'LKML'" <linux-kernel@vger.kernel.org>,
"Doug Smythies" <dsmythies@telus.net>
Subject: RE: [PATCH v2] cpufreq: intel_pstate: Rework iowait boosting to be less aggressive
Date: Sun, 17 Feb 2019 11:25:37 -0800 [thread overview]
Message-ID: <000c01d4c6f6$914a7f20$b3df7d60$@net> (raw)
In-Reply-To: <16144228.tcT5YVROcV@aspire.rjw.lan>
On 2019.02.07 03:51 Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> The current iowait boosting mechanism in intel_pstate_update_util()
> is quite aggressive, as it goes to the maximum P-state right away,
> and may cause excessive amounts of energy to be used, which is not
> desirable and arguably isn't necessary too.
>
> Follow commit a5a0809bc58e ("cpufreq: schedutil: Make iowait boost
> more energy efficient") that reworked the analogous iowait boost
> mechanism in the schedutil governor and make the iowait boosting
> in intel_pstate_update_util() work along the same lines.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>
> -> v2:
> * Follow the Doug's suggestion and drop the immediate jump to
> max P-state if boost is max. The code is simpler this way and
> the perf impact should not be noticeable on average.
Hi Rafael,
Something has broken on my incoming e-mail sorting stuff, and I
missed this one (and some others).
This V2 is not actually what I was proposing. I was O.K. with
the immediate jump, but I didn't want the set_pstate step
by-passed if it was already at max because that would also
by-pass the trace sample, if it was enabled.
Anyway, this V2 seems O.K. to me. I tested it compared to V1
and, as you mentioned, wasn't able to detect any energy consumption
or performance differences.
... Doug
next prev parent reply other threads:[~2019-02-17 19:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-31 0:04 [PATCH] cpufreq: intel_pstate: Rework iowait boosting to be less aggressive Rafael J. Wysocki
2019-02-07 11:51 ` [PATCH v2] " Rafael J. Wysocki
2019-02-17 19:25 ` Doug Smythies [this message]
2019-02-18 22:03 ` Rafael J. Wysocki
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