[PATCH 3.13 39/40] intel_pstate: Take core C0 time into account for core busy calculation

From: Greg Kroah-Hartman
Date: Tue Feb 18 2014 - 17:48:37 EST


3.13-stable review patch. If anyone has any objections, please let me know.

------------------

From: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx>

commit fcb6a15c2e7e76d493e6f91ea889ab40e1c643a4 upstream.

Take non-idle time into account when calculating core busy time.
This ensures that intel_pstate will notice a decrease in load.

References: https://bugzilla.kernel.org/show_bug.cgi?id=66581
Cc: 3.10+ <stable@xxxxxxxxxxxxxxx> # 3.10+
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 | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)

--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -54,6 +54,7 @@ struct sample {
int32_t core_pct_busy;
u64 aperf;
u64 mperf;
+ unsigned long long tsc;
int freq;
};

@@ -88,6 +89,7 @@ struct cpudata {

u64 prev_aperf;
u64 prev_mperf;
+ unsigned long long prev_tsc;
int sample_ptr;
struct sample samples[SAMPLE_COUNT];
};
@@ -499,11 +501,17 @@ static inline void intel_pstate_calc_bus
struct sample *sample)
{
u64 core_pct;
- core_pct = div64_u64(int_tofp(sample->aperf * 100),
- sample->mperf);
- sample->freq = fp_toint(cpu->pstate.max_pstate * core_pct * 1000);
+ u64 c0_pct;

- sample->core_pct_busy = core_pct;
+ core_pct = div64_u64(sample->aperf * 100, sample->mperf);
+
+ c0_pct = div64_u64(sample->mperf * 100, sample->tsc);
+ sample->freq = fp_toint(
+ mul_fp(int_tofp(cpu->pstate.max_pstate),
+ int_tofp(core_pct * 1000)));
+
+ sample->core_pct_busy = mul_fp(int_tofp(core_pct),
+ div_fp(int_tofp(c0_pct + 1), int_tofp(100)));
}

static inline void intel_pstate_sample(struct cpudata *cpu)


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/