04d4e665a6
Refer to housekeeping APIs using single feature types instead of flags. This prevents from passing multiple isolation features at once to housekeeping interfaces, which soon won't be possible anymore as each isolation features will have their own cpumask. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Juri Lelli <juri.lelli@redhat.com> Reviewed-by: Phil Auld <pauld@redhat.com> Link: https://lore.kernel.org/r/20220207155910.527133-5-frederic@kernel.org
151 lines
3.4 KiB
C
151 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* x86 APERF/MPERF KHz calculation for
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* /sys/.../cpufreq/scaling_cur_freq
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*
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* Copyright (C) 2017 Intel Corp.
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* Author: Len Brown <len.brown@intel.com>
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*/
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#include <linux/delay.h>
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#include <linux/ktime.h>
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#include <linux/math64.h>
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#include <linux/percpu.h>
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#include <linux/cpufreq.h>
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#include <linux/smp.h>
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#include <linux/sched/isolation.h>
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#include <linux/rcupdate.h>
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#include "cpu.h"
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struct aperfmperf_sample {
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unsigned int khz;
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atomic_t scfpending;
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ktime_t time;
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u64 aperf;
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u64 mperf;
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};
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static DEFINE_PER_CPU(struct aperfmperf_sample, samples);
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#define APERFMPERF_CACHE_THRESHOLD_MS 10
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#define APERFMPERF_REFRESH_DELAY_MS 10
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#define APERFMPERF_STALE_THRESHOLD_MS 1000
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/*
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* aperfmperf_snapshot_khz()
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* On the current CPU, snapshot APERF, MPERF, and jiffies
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* unless we already did it within 10ms
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* calculate kHz, save snapshot
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*/
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static void aperfmperf_snapshot_khz(void *dummy)
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{
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u64 aperf, aperf_delta;
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u64 mperf, mperf_delta;
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struct aperfmperf_sample *s = this_cpu_ptr(&samples);
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unsigned long flags;
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local_irq_save(flags);
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rdmsrl(MSR_IA32_APERF, aperf);
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rdmsrl(MSR_IA32_MPERF, mperf);
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local_irq_restore(flags);
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aperf_delta = aperf - s->aperf;
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mperf_delta = mperf - s->mperf;
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/*
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* There is no architectural guarantee that MPERF
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* increments faster than we can read it.
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*/
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if (mperf_delta == 0)
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return;
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s->time = ktime_get();
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s->aperf = aperf;
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s->mperf = mperf;
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s->khz = div64_u64((cpu_khz * aperf_delta), mperf_delta);
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atomic_set_release(&s->scfpending, 0);
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}
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static bool aperfmperf_snapshot_cpu(int cpu, ktime_t now, bool wait)
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{
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s64 time_delta = ktime_ms_delta(now, per_cpu(samples.time, cpu));
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struct aperfmperf_sample *s = per_cpu_ptr(&samples, cpu);
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/* Don't bother re-computing within the cache threshold time. */
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if (time_delta < APERFMPERF_CACHE_THRESHOLD_MS)
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return true;
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if (!atomic_xchg(&s->scfpending, 1) || wait)
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smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, wait);
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/* Return false if the previous iteration was too long ago. */
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return time_delta <= APERFMPERF_STALE_THRESHOLD_MS;
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}
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unsigned int aperfmperf_get_khz(int cpu)
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{
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if (!cpu_khz)
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return 0;
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if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
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return 0;
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if (!housekeeping_cpu(cpu, HK_TYPE_MISC))
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return 0;
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if (rcu_is_idle_cpu(cpu))
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return 0; /* Idle CPUs are completely uninteresting. */
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aperfmperf_snapshot_cpu(cpu, ktime_get(), true);
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return per_cpu(samples.khz, cpu);
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}
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void arch_freq_prepare_all(void)
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{
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ktime_t now = ktime_get();
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bool wait = false;
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int cpu;
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if (!cpu_khz)
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return;
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if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
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return;
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for_each_online_cpu(cpu) {
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if (!housekeeping_cpu(cpu, HK_TYPE_MISC))
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continue;
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if (rcu_is_idle_cpu(cpu))
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continue; /* Idle CPUs are completely uninteresting. */
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if (!aperfmperf_snapshot_cpu(cpu, now, false))
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wait = true;
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}
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if (wait)
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msleep(APERFMPERF_REFRESH_DELAY_MS);
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}
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unsigned int arch_freq_get_on_cpu(int cpu)
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{
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struct aperfmperf_sample *s = per_cpu_ptr(&samples, cpu);
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if (!cpu_khz)
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return 0;
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if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
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return 0;
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if (!housekeeping_cpu(cpu, HK_TYPE_MISC))
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return 0;
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if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true))
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return per_cpu(samples.khz, cpu);
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msleep(APERFMPERF_REFRESH_DELAY_MS);
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atomic_set(&s->scfpending, 1);
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smp_mb(); /* ->scfpending before smp_call_function_single(). */
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smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1);
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return per_cpu(samples.khz, cpu);
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}
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