diff options
| -rw-r--r-- | arch/x86/kernel/cpu/Makefile | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/aperfmperf.c | 79 | ||||
| -rw-r--r-- | drivers/cpufreq/cpufreq.c | 12 | ||||
| -rw-r--r-- | include/linux/cpufreq.h | 2 |
4 files changed, 93 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile index 52000010c62e..cdf82492b770 100644 --- a/arch/x86/kernel/cpu/Makefile +++ b/arch/x86/kernel/cpu/Makefile @@ -21,6 +21,7 @@ obj-y += common.o obj-y += rdrand.o obj-y += match.o obj-y += bugs.o +obj-$(CONFIG_CPU_FREQ) += aperfmperf.o obj-$(CONFIG_PROC_FS) += proc.o obj-$(CONFIG_X86_FEATURE_NAMES) += capflags.o powerflags.o diff --git a/arch/x86/kernel/cpu/aperfmperf.c b/arch/x86/kernel/cpu/aperfmperf.c new file mode 100644 index 000000000000..d869c8671e36 --- /dev/null +++ b/arch/x86/kernel/cpu/aperfmperf.c @@ -0,0 +1,79 @@ +/* + * x86 APERF/MPERF KHz calculation for + * /sys/.../cpufreq/scaling_cur_freq + * + * Copyright (C) 2017 Intel Corp. + * Author: Len Brown <len.brown@intel.com> + * + * This file is licensed under GPLv2. + */ + +#include <linux/jiffies.h> +#include <linux/math64.h> +#include <linux/percpu.h> +#include <linux/smp.h> + +struct aperfmperf_sample { + unsigned int khz; + unsigned long jiffies; + u64 aperf; + u64 mperf; +}; + +static DEFINE_PER_CPU(struct aperfmperf_sample, samples); + +/* + * aperfmperf_snapshot_khz() + * On the current CPU, snapshot APERF, MPERF, and jiffies + * unless we already did it within 10ms + * calculate kHz, save snapshot + */ +static void aperfmperf_snapshot_khz(void *dummy) +{ + u64 aperf, aperf_delta; + u64 mperf, mperf_delta; + struct aperfmperf_sample *s = this_cpu_ptr(&samples); + + /* Don't bother re-computing within 10 ms */ + if (time_before(jiffies, s->jiffies + HZ/100)) + return; + + rdmsrl(MSR_IA32_APERF, aperf); + rdmsrl(MSR_IA32_MPERF, mperf); + + aperf_delta = aperf - s->aperf; + mperf_delta = mperf - s->mperf; + + /* + * There is no architectural guarantee that MPERF + * increments faster than we can read it. + */ + if (mperf_delta == 0) + return; + + /* + * if (cpu_khz * aperf_delta) fits into ULLONG_MAX, then + * khz = (cpu_khz * aperf_delta) / mperf_delta + */ + if (div64_u64(ULLONG_MAX, cpu_khz) > aperf_delta) + s->khz = div64_u64((cpu_khz * aperf_delta), mperf_delta); + else /* khz = aperf_delta / (mperf_delta / cpu_khz) */ + s->khz = div64_u64(aperf_delta, + div64_u64(mperf_delta, cpu_khz)); + s->jiffies = jiffies; + s->aperf = aperf; + s->mperf = mperf; +} + +unsigned int arch_freq_get_on_cpu(int cpu) +{ + if (!cpu_khz) + return 0; + + if (!static_cpu_has(X86_FEATURE_APERFMPERF)) + return 0; + + smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1); + + return per_cpu(samples.khz, cpu); +} diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 26b643d57847..6e7424d12de9 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -632,11 +632,21 @@ show_one(cpuinfo_transition_latency, cpuinfo.transition_latency); show_one(scaling_min_freq, min); show_one(scaling_max_freq, max); +__weak unsigned int arch_freq_get_on_cpu(int cpu) +{ + return 0; +} + static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf) { ssize_t ret; + unsigned int freq; - if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get) + freq = arch_freq_get_on_cpu(policy->cpu); + if (freq) + ret = sprintf(buf, "%u\n", freq); + else if (cpufreq_driver && cpufreq_driver->setpolicy && + cpufreq_driver->get) ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu)); else ret = sprintf(buf, "%u\n", policy->cur); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index a5ce0bbeadb5..905117bd5012 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -883,6 +883,8 @@ static inline bool policy_has_boost_freq(struct cpufreq_policy *policy) } #endif +extern unsigned int arch_freq_get_on_cpu(int cpu); + /* the following are really really optional */ extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs; extern struct freq_attr cpufreq_freq_attr_scaling_boost_freqs; |