From: "Doug Smythies" <dsmythies@telus.net>
To: 'Kristen Carlson Accardi' <kristen@linux.intel.com>
Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org,
Doug Smythies <dsmythies@telus.net>
Subject: RE: [PATCH 2/5] intel_pstate: Use C0 time for busy calculations (again).
Date: Wed, 6 May 2015 23:17:22 -0700 [thread overview]
Message-ID: <000a01d0888d$7bf56370$73e02a50$@net> (raw)
In-Reply-To: <20150506122027.568b0522@kcaccard-desk.amr.corp.intel.com>
On 2015.05.06 Kristen Carlson Accardi wrote:
> On Sat, 11 Apr 2015 21:10:27 -0700 Doug Smythies <doug.smythies@gmail.com> wrote:
>> This patch brings back the inclusion of C0 time
>> for the calculation of core_busy.
...
>> + core_pct = int_tofp(sample->mperf) * int_tofp(1000);
>> + core_pct = div64_u64(core_pct, int_tofp(sample->tsc));
> FYI - It's not actually valid to use the contents of mperf without aperf
> according the the intel SDM:
> "Only the IA32_APERF/IA32_MPERF ratio is architecturally defined;
> software should not attach meaning to the content of the individual of IA32_APERF or IA32_MPERF MSRs."
> There is no guarantee mperf and tsc are using the same clock.
I was just bringing back code that used to be there.
Reference: fcb6a15c2e7e76d493e6f91ea889ab40e1c643a4 2014.02.03 Dirk Brandewie
I do not know of another way to calculate load, but I will try to look at
how the acpi-cpufreq driver does it.
On my computer, available clock sources are: tsc hpet acpi_pm
and it seems plenty close enough using any one of the 3.
next prev parent reply other threads:[~2015-05-07 6:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-12 4:10 [PATCH 0/5] intel_pstate: Use C0 time, calculate target pstate directly Doug Smythies
2015-04-12 4:10 ` [PATCH 1/5] intel_pstate: Add tsc collection and keep previous target pstate. Add both to trace Doug Smythies
2015-04-29 16:57 ` Kristen Carlson Accardi
2015-05-04 23:34 ` Rafael J. Wysocki
2015-04-12 4:10 ` [PATCH 2/5] intel_pstate: Use C0 time for busy calculations (again) Doug Smythies
2015-05-06 19:20 ` Kristen Carlson Accardi
2015-05-07 6:17 ` Doug Smythies [this message]
2015-04-12 4:10 ` [PATCH 3/5] intel_pstate: Calculate target pstate directly Doug Smythies
2015-04-12 4:10 ` [PATCH 4/5] intel_pstate: Compensate for intermediate durations (v2) Doug Smythies
2015-04-12 4:10 ` [PATCH 5/5] intel_pstate: Adjust default IIR filter gain Doug Smythies
2015-04-13 16:32 ` [PATCH 0/5] intel_pstate: Use C0 time, calculate target pstate directly Kristen Carlson Accardi
2015-04-13 21:16 ` Doug Smythies
2015-04-16 16:35 ` Doug Smythies
2015-04-17 0:46 ` Rafael J. Wysocki
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