This is a note to let you know that I've just added the patch titled
intel_pstate: Improve initial busy calculation
to the 3.14-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:
intel_pstate-improve-initial-busy-calculation.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From bf8102228a8bf053051f311e5486042fe0542894 Mon Sep 17 00:00:00 2001
From: Doug Smythies <dsmythies@xxxxxxxxx>
Date: Fri, 30 May 2014 10:10:57 -0700
Subject: intel_pstate: Improve initial busy calculation
From: Doug Smythies <dsmythies@xxxxxxxxx>
commit bf8102228a8bf053051f311e5486042fe0542894 upstream.
This change makes the busy calculation using 64 bit math which prevents
overflow for large values of aperf/mperf.
Signed-off-by: Doug Smythies <dsmythies@xxxxxxxxx>
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 | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -563,16 +563,19 @@ static void intel_pstate_get_cpu_pstates
static inline void intel_pstate_calc_busy(struct cpudata *cpu,
struct sample *sample)
{
- int32_t core_pct;
+ int64_t core_pct;
+ int32_t rem;
- core_pct = div_fp(int_tofp((sample->aperf)),
- int_tofp((sample->mperf)));
- core_pct = mul_fp(core_pct, int_tofp(100));
+ core_pct = int_tofp(sample->aperf) * int_tofp(100);
+ core_pct = div_u64_rem(core_pct, int_tofp(sample->mperf), &rem);
+
+ if ((rem << 1) >= int_tofp(sample->mperf))
+ core_pct += 1;
sample->freq = fp_toint(
mul_fp(int_tofp(cpu->pstate.max_pstate * 1000), core_pct));
- sample->core_pct_busy = core_pct;
+ sample->core_pct_busy = (int32_t)core_pct;
}
static inline void intel_pstate_sample(struct cpudata *cpu)
Patches currently in stable-queue which might be from dsmythies@xxxxxxxxx are
queue-3.14/intel_pstate-improve-initial-busy-calculation.patch
queue-3.14/intel_pstate-remove-c0-tracking.patch
queue-3.14/intel_pstate-correct-rounding-in-busy-calculation.patch
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