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cpufreq / intel_pstate: fix ffmpeg regression 

The ffmpeg benchmark in the phoronix test suite has threads on
multiple cores that rely on the progress on of threads on other cores
and ping pong back and forth fast enough to make the core appear less
busy than it "should" be.  If the core has been at minimum p-state for
a while bump the pstate up to kick the core to see if it is in this
ping pong state.  If the core is truly idle the p-state will be
reduced at the next sample time.  If the core makes more progress it
will send more work to the thread bringing both threads out of the
ping pong scenario and the p-state will be selected normally.

This fixes a performance regression of approximately 30%

Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Dirk Brandewie 2013-05-07 08:20:27 -07:00 committed by Rafael J. Wysocki
parent d8f469e9cf
commit ca182aee38
1 changed files with 2 additions and 8 deletions
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10
drivers/cpufreq/intel_pstate.c
View File

@ -551,22 +551,16 @@ static void intel_pstate_timer_func(unsigned long __data)
struct cpudata *cpu = (struct cpudata *) __data;
intel_pstate_sample(cpu);
intel_pstate_adjust_busy_pstate(cpu);
if (!cpu->idle_mode)
intel_pstate_adjust_busy_pstate(cpu);
else
intel_pstate_adjust_idle_pstate(cpu);
#if defined(XPERF_FIX)
if (cpu->pstate.current_pstate == cpu->pstate.min_pstate) {
cpu->min_pstate_count++;
if (!(cpu->min_pstate_count % 5)) {
intel_pstate_set_pstate(cpu, cpu->pstate.max_pstate);
intel_pstate_idle_mode(cpu);
}
} else
cpu->min_pstate_count = 0;
#endif
intel_pstate_set_sample_time(cpu);
}