diff mbox

[09/17] cpufreq: intel_pstate: Keep values in aperf/mperf in full precision

Message ID 1405697848-13546-10-git-send-email-dirk.j.brandewie@intel.com (mailing list archive)
State Superseded, archived
Headers show

Commit Message

dirk.brandewie@gmail.com July 18, 2014, 3:37 p.m. UTC 
From: Stratos Karafotis <stratosk@semaphore.gr>

Currently we shift right aperf and mperf variables by FRAC_BITS
to prevent overflow when we convert them to fix point numbers
(shift left by FRAC_BITS).

But this is not necessary, because we actually use delta aperf and mperf
which are much less than APERF and MPERF values.

So, use the unmodified APERF and MPERF values in calculation.
This also adds 8 bits in precision, although the gain is insignificant.
Also, use div64_u64 instead of div_u64 in calc_busy() to avoid
overflow of sample->mperf as divisor.

Signed-off-by: Stratos Karafotis <stratosk@semaphore.gr>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
---
 drivers/cpufreq/intel_pstate.c | 3 ---
 1 file changed, 3 deletions(-)
diff mbox

Patch

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index ff3c562..129ffb2 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -584,9 +584,6 @@  static inline void intel_pstate_sample(struct cpudata *cpu)
 	rdmsrl(MSR_IA32_MPERF, mperf);
 	local_irq_restore(flags);
 
-	aperf = aperf >> FRAC_BITS;
-	mperf = mperf >> FRAC_BITS;
-
 	cpu->last_sample_time = cpu->sample.time;
 	cpu->sample.time = ktime_get();
 	cpu->sample.aperf = aperf;