This is a note to let you know that I've just added the patch titled
cpufreq / intel_pstate: remove idle time and duration from sample and calculations
to the 3.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
cpufreq-intel_pstate-remove-idle-time-and-duration-from-sample-and-calculations.patch
and it can be found in the queue-3.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1abc4b20b85b42e8573957e54b193385cf48b0d6 Mon Sep 17 00:00:00 2001
From: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
Date: Tue, 7 May 2013 08:20:25 -0700
Subject: cpufreq / intel_pstate: remove idle time and duration from sample and calculations
From: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
commit 1abc4b20b85b42e8573957e54b193385cf48b0d6 upstream.
Idle time is taken into account in the APERF/MPERF ratio calculation
there is no reason for the driver to track it seperately. This
reduces the work in the driver and makes the code more readable.
Removal of the tracking of sample duration removes the possibility of
the divide by zero exception when the duration is sub 1us
References: https://bugzilla.kernel.org/show_bug.cgi?id=56691
Reported-by: Mike Lothian <mike@xxxxxxxxxxxxxx>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/cpufreq/intel_pstate.c | 43 ++++++-----------------------------------
1 file changed, 7 insertions(+), 36 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -48,12 +48,7 @@ static inline int32_t div_fp(int32_t x,
}
struct sample {
- ktime_t start_time;
- ktime_t end_time;
int core_pct_busy;
- int pstate_pct_busy;
- u64 duration_us;
- u64 idletime_us;
u64 aperf;
u64 mperf;
int freq;
@@ -91,8 +86,6 @@ struct cpudata {
int min_pstate_count;
int idle_mode;
- ktime_t prev_sample;
- u64 prev_idle_time_us;
u64 prev_aperf;
u64 prev_mperf;
int sample_ptr;
@@ -450,48 +443,26 @@ static inline void intel_pstate_calc_bus
struct sample *sample)
{
u64 core_pct;
- sample->pstate_pct_busy = 100 - div64_u64(
- sample->idletime_us * 100,
- sample->duration_us);
core_pct = div64_u64(sample->aperf * 100, sample->mperf);
sample->freq = cpu->pstate.max_pstate * core_pct * 1000;
- sample->core_pct_busy = div_s64((sample->pstate_pct_busy * core_pct),
- 100);
+ sample->core_pct_busy = core_pct;
}
static inline void intel_pstate_sample(struct cpudata *cpu)
{
- ktime_t now;
- u64 idle_time_us;
u64 aperf, mperf;
- now = ktime_get();
- idle_time_us = get_cpu_idle_time_us(cpu->cpu, NULL);
-
rdmsrl(MSR_IA32_APERF, aperf);
rdmsrl(MSR_IA32_MPERF, mperf);
- /* for the first sample, don't actually record a sample, just
- * set the baseline */
- if (cpu->prev_idle_time_us > 0) {
- cpu->sample_ptr = (cpu->sample_ptr + 1) % SAMPLE_COUNT;
- cpu->samples[cpu->sample_ptr].start_time = cpu->prev_sample;
- cpu->samples[cpu->sample_ptr].end_time = now;
- cpu->samples[cpu->sample_ptr].duration_us =
- ktime_us_delta(now, cpu->prev_sample);
- cpu->samples[cpu->sample_ptr].idletime_us =
- idle_time_us - cpu->prev_idle_time_us;
-
- cpu->samples[cpu->sample_ptr].aperf = aperf;
- cpu->samples[cpu->sample_ptr].mperf = mperf;
- cpu->samples[cpu->sample_ptr].aperf -= cpu->prev_aperf;
- cpu->samples[cpu->sample_ptr].mperf -= cpu->prev_mperf;
+ cpu->sample_ptr = (cpu->sample_ptr + 1) % SAMPLE_COUNT;
+ cpu->samples[cpu->sample_ptr].aperf = aperf;
+ cpu->samples[cpu->sample_ptr].mperf = mperf;
+ cpu->samples[cpu->sample_ptr].aperf -= cpu->prev_aperf;
+ cpu->samples[cpu->sample_ptr].mperf -= cpu->prev_mperf;
- intel_pstate_calc_busy(cpu, &cpu->samples[cpu->sample_ptr]);
- }
+ intel_pstate_calc_busy(cpu, &cpu->samples[cpu->sample_ptr]);
- cpu->prev_sample = now;
- cpu->prev_idle_time_us = idle_time_us;
cpu->prev_aperf = aperf;
cpu->prev_mperf = mperf;
}
Patches currently in stable-queue which might be from dirk.j.brandewie@xxxxxxxxx are
queue-3.9/cpufreq-intel_pstate-use-lowest-requested-max-performance.patch
queue-3.9/cpufreq-intel_pstate-remove-idle-time-and-duration-from-sample-and-calculations.patch
queue-3.9/cpufreq-intel_pstate-fix-ffmpeg-regression.patch
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