461 lines
11 KiB
C
461 lines
11 KiB
C
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// 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/cpufreq.h>
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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/rcupdate.h>
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#include <linux/sched/isolation.h>
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#include <linux/sched/topology.h>
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#include <linux/smp.h>
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#include <linux/syscore_ops.h>
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#include <asm/cpu.h>
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#include <asm/cpu_device_id.h>
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#include <asm/intel-family.h>
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#include "cpu.h"
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struct aperfmperf {
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seqcount_t seq;
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unsigned long last_update;
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u64 acnt;
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u64 mcnt;
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u64 aperf;
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u64 mperf;
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};
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static DEFINE_PER_CPU_SHARED_ALIGNED(struct aperfmperf, cpu_samples) = {
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.seq = SEQCNT_ZERO(cpu_samples.seq)
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};
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static void init_counter_refs(void)
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{
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u64 aperf, mperf;
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rdmsrl(MSR_IA32_APERF, aperf);
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rdmsrl(MSR_IA32_MPERF, mperf);
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this_cpu_write(cpu_samples.aperf, aperf);
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this_cpu_write(cpu_samples.mperf, mperf);
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}
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#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
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/*
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* APERF/MPERF frequency ratio computation.
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*
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* The scheduler wants to do frequency invariant accounting and needs a <1
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* ratio to account for the 'current' frequency, corresponding to
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* freq_curr / freq_max.
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*
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* Since the frequency freq_curr on x86 is controlled by micro-controller and
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* our P-state setting is little more than a request/hint, we need to observe
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* the effective frequency 'BusyMHz', i.e. the average frequency over a time
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* interval after discarding idle time. This is given by:
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*
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* BusyMHz = delta_APERF / delta_MPERF * freq_base
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*
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* where freq_base is the max non-turbo P-state.
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*
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* The freq_max term has to be set to a somewhat arbitrary value, because we
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* can't know which turbo states will be available at a given point in time:
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* it all depends on the thermal headroom of the entire package. We set it to
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* the turbo level with 4 cores active.
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*
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* Benchmarks show that's a good compromise between the 1C turbo ratio
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* (freq_curr/freq_max would rarely reach 1) and something close to freq_base,
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* which would ignore the entire turbo range (a conspicuous part, making
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* freq_curr/freq_max always maxed out).
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*
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* An exception to the heuristic above is the Atom uarch, where we choose the
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* highest turbo level for freq_max since Atom's are generally oriented towards
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* power efficiency.
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*
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* Setting freq_max to anything less than the 1C turbo ratio makes the ratio
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* freq_curr / freq_max to eventually grow >1, in which case we clip it to 1.
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*/
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DEFINE_STATIC_KEY_FALSE(arch_scale_freq_key);
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static u64 arch_turbo_freq_ratio = SCHED_CAPACITY_SCALE;
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static u64 arch_max_freq_ratio = SCHED_CAPACITY_SCALE;
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void arch_set_max_freq_ratio(bool turbo_disabled)
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{
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arch_max_freq_ratio = turbo_disabled ? SCHED_CAPACITY_SCALE :
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arch_turbo_freq_ratio;
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}
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EXPORT_SYMBOL_GPL(arch_set_max_freq_ratio);
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static bool __init turbo_disabled(void)
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{
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u64 misc_en;
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int err;
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err = rdmsrl_safe(MSR_IA32_MISC_ENABLE, &misc_en);
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if (err)
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return false;
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return (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
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}
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static bool __init slv_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
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{
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int err;
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err = rdmsrl_safe(MSR_ATOM_CORE_RATIOS, base_freq);
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if (err)
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return false;
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err = rdmsrl_safe(MSR_ATOM_CORE_TURBO_RATIOS, turbo_freq);
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if (err)
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return false;
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*base_freq = (*base_freq >> 16) & 0x3F; /* max P state */
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*turbo_freq = *turbo_freq & 0x3F; /* 1C turbo */
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return true;
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}
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#define X86_MATCH(model) \
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X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6, \
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INTEL_FAM6_##model, X86_FEATURE_APERFMPERF, NULL)
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static const struct x86_cpu_id has_knl_turbo_ratio_limits[] __initconst = {
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X86_MATCH(XEON_PHI_KNL),
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X86_MATCH(XEON_PHI_KNM),
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{}
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};
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static const struct x86_cpu_id has_skx_turbo_ratio_limits[] __initconst = {
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X86_MATCH(SKYLAKE_X),
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{}
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};
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static const struct x86_cpu_id has_glm_turbo_ratio_limits[] __initconst = {
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X86_MATCH(ATOM_GOLDMONT),
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X86_MATCH(ATOM_GOLDMONT_D),
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X86_MATCH(ATOM_GOLDMONT_PLUS),
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{}
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};
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static bool __init knl_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq,
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int num_delta_fratio)
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{
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int fratio, delta_fratio, found;
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int err, i;
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u64 msr;
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err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
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if (err)
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return false;
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*base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
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err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
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if (err)
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return false;
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fratio = (msr >> 8) & 0xFF;
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i = 16;
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found = 0;
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do {
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if (found >= num_delta_fratio) {
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*turbo_freq = fratio;
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return true;
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}
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delta_fratio = (msr >> (i + 5)) & 0x7;
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if (delta_fratio) {
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found += 1;
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fratio -= delta_fratio;
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}
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i += 8;
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} while (i < 64);
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return true;
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}
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static bool __init skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
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{
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u64 ratios, counts;
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u32 group_size;
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int err, i;
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err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
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if (err)
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return false;
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*base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
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err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &ratios);
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if (err)
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return false;
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err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT1, &counts);
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if (err)
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return false;
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for (i = 0; i < 64; i += 8) {
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group_size = (counts >> i) & 0xFF;
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if (group_size >= size) {
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*turbo_freq = (ratios >> i) & 0xFF;
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return true;
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}
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}
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return false;
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}
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static bool __init core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
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{
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u64 msr;
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int err;
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err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
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if (err)
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return false;
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err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
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if (err)
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return false;
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*base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
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*turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
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/* The CPU may have less than 4 cores */
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if (!*turbo_freq)
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*turbo_freq = msr & 0xFF; /* 1C turbo */
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return true;
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}
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static bool __init intel_set_max_freq_ratio(void)
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{
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u64 base_freq, turbo_freq;
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u64 turbo_ratio;
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if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
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goto out;
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if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
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skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
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goto out;
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if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
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knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
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goto out;
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if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
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skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
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goto out;
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if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
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goto out;
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return false;
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out:
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/*
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* Some hypervisors advertise X86_FEATURE_APERFMPERF
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* but then fill all MSR's with zeroes.
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* Some CPUs have turbo boost but don't declare any turbo ratio
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* in MSR_TURBO_RATIO_LIMIT.
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*/
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if (!base_freq || !turbo_freq) {
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pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n");
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return false;
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}
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turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
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if (!turbo_ratio) {
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pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
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return false;
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}
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arch_turbo_freq_ratio = turbo_ratio;
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arch_set_max_freq_ratio(turbo_disabled());
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return true;
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}
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#ifdef CONFIG_PM_SLEEP
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static struct syscore_ops freq_invariance_syscore_ops = {
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.resume = init_counter_refs,
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};
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static void register_freq_invariance_syscore_ops(void)
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{
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register_syscore_ops(&freq_invariance_syscore_ops);
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}
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#else
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static inline void register_freq_invariance_syscore_ops(void) {}
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#endif
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static void freq_invariance_enable(void)
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{
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if (static_branch_unlikely(&arch_scale_freq_key)) {
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WARN_ON_ONCE(1);
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return;
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}
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static_branch_enable(&arch_scale_freq_key);
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register_freq_invariance_syscore_ops();
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pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
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}
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void freq_invariance_set_perf_ratio(u64 ratio, bool turbo_disabled)
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{
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arch_turbo_freq_ratio = ratio;
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arch_set_max_freq_ratio(turbo_disabled);
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freq_invariance_enable();
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}
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static void __init bp_init_freq_invariance(void)
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{
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if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
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return;
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if (intel_set_max_freq_ratio())
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freq_invariance_enable();
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}
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static void disable_freq_invariance_workfn(struct work_struct *work)
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{
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int cpu;
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static_branch_disable(&arch_scale_freq_key);
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/*
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* Set arch_freq_scale to a default value on all cpus
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* This negates the effect of scaling
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*/
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for_each_possible_cpu(cpu)
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per_cpu(arch_freq_scale, cpu) = SCHED_CAPACITY_SCALE;
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}
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static DECLARE_WORK(disable_freq_invariance_work,
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disable_freq_invariance_workfn);
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DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
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static void scale_freq_tick(u64 acnt, u64 mcnt)
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{
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u64 freq_scale;
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if (!arch_scale_freq_invariant())
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return;
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if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
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goto error;
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if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt)
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goto error;
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freq_scale = div64_u64(acnt, mcnt);
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if (!freq_scale)
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goto error;
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if (freq_scale > SCHED_CAPACITY_SCALE)
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freq_scale = SCHED_CAPACITY_SCALE;
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this_cpu_write(arch_freq_scale, freq_scale);
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return;
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error:
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pr_warn("Scheduler frequency invariance went wobbly, disabling!\n");
|
||
|
|
schedule_work(&disable_freq_invariance_work);
|
||
|
|
}
|
||
|
|
#else
|
||
|
|
static inline void bp_init_freq_invariance(void) { }
|
||
|
|
static inline void scale_freq_tick(u64 acnt, u64 mcnt) { }
|
||
|
|
#endif /* CONFIG_X86_64 && CONFIG_SMP */
|
||
|
|
|
||
|
|
void arch_scale_freq_tick(void)
|
||
|
|
{
|
||
|
|
struct aperfmperf *s = this_cpu_ptr(&cpu_samples);
|
||
|
|
u64 acnt, mcnt, aperf, mperf;
|
||
|
|
|
||
|
|
if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
|
||
|
|
return;
|
||
|
|
|
||
|
|
rdmsrl(MSR_IA32_APERF, aperf);
|
||
|
|
rdmsrl(MSR_IA32_MPERF, mperf);
|
||
|
|
acnt = aperf - s->aperf;
|
||
|
|
mcnt = mperf - s->mperf;
|
||
|
|
|
||
|
|
s->aperf = aperf;
|
||
|
|
s->mperf = mperf;
|
||
|
|
|
||
|
|
raw_write_seqcount_begin(&s->seq);
|
||
|
|
s->last_update = jiffies;
|
||
|
|
s->acnt = acnt;
|
||
|
|
s->mcnt = mcnt;
|
||
|
|
raw_write_seqcount_end(&s->seq);
|
||
|
|
|
||
|
|
scale_freq_tick(acnt, mcnt);
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Discard samples older than the define maximum sample age of 20ms. There
|
||
|
|
* is no point in sending IPIs in such a case. If the scheduler tick was
|
||
|
|
* not running then the CPU is either idle or isolated.
|
||
|
|
*/
|
||
|
|
#define MAX_SAMPLE_AGE ((unsigned long)HZ / 50)
|
||
|
|
|
||
|
|
unsigned int arch_freq_get_on_cpu(int cpu)
|
||
|
|
{
|
||
|
|
struct aperfmperf *s = per_cpu_ptr(&cpu_samples, cpu);
|
||
|
|
unsigned int seq, freq;
|
||
|
|
unsigned long last;
|
||
|
|
u64 acnt, mcnt;
|
||
|
|
|
||
|
|
if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
|
||
|
|
goto fallback;
|
||
|
|
|
||
|
|
do {
|
||
|
|
seq = raw_read_seqcount_begin(&s->seq);
|
||
|
|
last = s->last_update;
|
||
|
|
acnt = s->acnt;
|
||
|
|
mcnt = s->mcnt;
|
||
|
|
} while (read_seqcount_retry(&s->seq, seq));
|
||
|
|
|
||
|
|
/*
|
||
|
|
* Bail on invalid count and when the last update was too long ago,
|
||
|
|
* which covers idle and NOHZ full CPUs.
|
||
|
|
*/
|
||
|
|
if (!mcnt || (jiffies - last) > MAX_SAMPLE_AGE)
|
||
|
|
goto fallback;
|
||
|
|
|
||
|
|
return div64_u64((cpu_khz * acnt), mcnt);
|
||
|
|
|
||
|
|
fallback:
|
||
|
|
freq = cpufreq_quick_get(cpu);
|
||
|
|
return freq ? freq : cpu_khz;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int __init bp_init_aperfmperf(void)
|
||
|
|
{
|
||
|
|
if (!cpu_feature_enabled(X86_FEATURE_APERFMPERF))
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
init_counter_refs();
|
||
|
|
bp_init_freq_invariance();
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
early_initcall(bp_init_aperfmperf);
|
||
|
|
|
||
|
|
void ap_init_aperfmperf(void)
|
||
|
|
{
|
||
|
|
if (cpu_feature_enabled(X86_FEATURE_APERFMPERF))
|
||
|
|
init_counter_refs();
|
||
|
|
}
|