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author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-04 07:48:54 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-06-04 07:48:54 -0700 |
commit | c717d1561493c58d030405c7e30e35459db31912 (patch) | |
tree | 85c3a9521691b437cb7a76b701331d3992361f46 | |
parent | 9e9a928eed8796a0a1aaed7e0b676db86ba84594 (diff) | |
parent | bf8102228a8bf053051f311e5486042fe0542894 (diff) | |
download | op-kernel-dev-c717d1561493c58d030405c7e30e35459db31912.zip op-kernel-dev-c717d1561493c58d030405c7e30e35459db31912.tar.gz |
Merge tag 'pm-3.15-final' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull intel pstate fixes from Rafael Wysocki:
"Final power management fixes for 3.15
- Taking non-idle time into account when calculating core busy time
was a mistake and led to a performance regression. Since the
problem it was supposed to address is now taken care of in a
different way, we don't need to do it any more, so drop the
non-idle time tracking from intel_pstate. Dirk Brandewie.
- Changing to fixed point math throughout the busy calculation
introduced rounding errors that adversely affect the accuracy of
intel_pstate's computations. Fix from Dirk Brandewie.
- The PID controller algorithm used by intel_pstate assumes that the
time interval between two adjacent samples will always be the same
which is not the case for deferable timers (used by intel_pstate)
when the system is idle. This leads to inaccurate predictions and
artificially increases convergence times for the minimum P-state.
Fix from Dirk Brandewie.
- intel_pstate carries out computations using 32-bit variables that
may overflow for large enough values of APERF/MPERF. Switch to
using 64-bit variables for computations, from Doug Smythies"
* tag 'pm-3.15-final' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
intel_pstate: Improve initial busy calculation
intel_pstate: add sample time scaling
intel_pstate: Correct rounding in busy calculation
intel_pstate: Remove C0 tracking
-rw-r--r-- | drivers/cpufreq/intel_pstate.c | 52 |
1 files changed, 31 insertions, 21 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index eab8ccf..db2e45b 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -40,10 +40,10 @@ #define BYT_TURBO_VIDS 0x66d -#define FRAC_BITS 6 +#define FRAC_BITS 8 #define int_tofp(X) ((int64_t)(X) << FRAC_BITS) #define fp_toint(X) ((X) >> FRAC_BITS) -#define FP_ROUNDUP(X) ((X) += 1 << FRAC_BITS) + static inline int32_t mul_fp(int32_t x, int32_t y) { @@ -59,8 +59,8 @@ struct sample { int32_t core_pct_busy; u64 aperf; u64 mperf; - unsigned long long tsc; int freq; + ktime_t time; }; struct pstate_data { @@ -98,9 +98,9 @@ struct cpudata { struct vid_data vid; struct _pid pid; + ktime_t last_sample_time; u64 prev_aperf; u64 prev_mperf; - unsigned long long prev_tsc; struct sample sample; }; @@ -200,7 +200,10 @@ static signed int pid_calc(struct _pid *pid, int32_t busy) pid->last_err = fp_error; result = pterm + mul_fp(pid->integral, pid->i_gain) + dterm; - + if (result >= 0) + result = result + (1 << (FRAC_BITS-1)); + else + result = result - (1 << (FRAC_BITS-1)); return (signed int)fp_toint(result); } @@ -560,47 +563,42 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu) static inline void intel_pstate_calc_busy(struct cpudata *cpu, struct sample *sample) { - int32_t core_pct; - int32_t c0_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)); - FP_ROUNDUP(core_pct); + core_pct = int_tofp(sample->aperf) * int_tofp(100); + core_pct = div_u64_rem(core_pct, int_tofp(sample->mperf), &rem); - c0_pct = div_fp(int_tofp(sample->mperf), int_tofp(sample->tsc)); + 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 = mul_fp(core_pct, c0_pct); + sample->core_pct_busy = (int32_t)core_pct; } static inline void intel_pstate_sample(struct cpudata *cpu) { u64 aperf, mperf; - unsigned long long tsc; rdmsrl(MSR_IA32_APERF, aperf); rdmsrl(MSR_IA32_MPERF, mperf); - tsc = native_read_tsc(); aperf = aperf >> FRAC_BITS; mperf = mperf >> FRAC_BITS; - tsc = tsc >> FRAC_BITS; + cpu->last_sample_time = cpu->sample.time; + cpu->sample.time = ktime_get(); cpu->sample.aperf = aperf; cpu->sample.mperf = mperf; - cpu->sample.tsc = tsc; cpu->sample.aperf -= cpu->prev_aperf; cpu->sample.mperf -= cpu->prev_mperf; - cpu->sample.tsc -= cpu->prev_tsc; intel_pstate_calc_busy(cpu, &cpu->sample); cpu->prev_aperf = aperf; cpu->prev_mperf = mperf; - cpu->prev_tsc = tsc; } static inline void intel_pstate_set_sample_time(struct cpudata *cpu) @@ -614,13 +612,25 @@ static inline void intel_pstate_set_sample_time(struct cpudata *cpu) static inline int32_t intel_pstate_get_scaled_busy(struct cpudata *cpu) { - int32_t core_busy, max_pstate, current_pstate; + int32_t core_busy, max_pstate, current_pstate, sample_ratio; + u32 duration_us; + u32 sample_time; core_busy = cpu->sample.core_pct_busy; max_pstate = int_tofp(cpu->pstate.max_pstate); current_pstate = int_tofp(cpu->pstate.current_pstate); core_busy = mul_fp(core_busy, div_fp(max_pstate, current_pstate)); - return FP_ROUNDUP(core_busy); + + sample_time = (pid_params.sample_rate_ms * USEC_PER_MSEC); + duration_us = (u32) ktime_us_delta(cpu->sample.time, + cpu->last_sample_time); + if (duration_us > sample_time * 3) { + sample_ratio = div_fp(int_tofp(sample_time), + int_tofp(duration_us)); + core_busy = mul_fp(core_busy, sample_ratio); + } + + return core_busy; } static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu) |