[patch 02/10] x86/smp: Move APERF/MPERF code where it belongs

From: Thomas Gleixner
Date: Fri Apr 15 2022 - 15:20:16 EST

as this can share code with the preexisting APERF/MPERF code.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/aperfmperf.c | 366 ++++++++++++++++++++++++++++++++++++++-
arch/x86/kernel/smpboot.c | 355 -------------------------------------
2 files changed, 362 insertions(+), 359 deletions(-)

--- a/arch/x86/kernel/cpu/aperfmperf.c
+++ b/arch/x86/kernel/cpu/aperfmperf.c
@@ -6,15 +6,19 @@
* Copyright (C) 2017 Intel Corp.
* Author: Len Brown <len.brown@xxxxxxxxx>
*/
-
+#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/ktime.h>
#include <linux/math64.h>
#include <linux/percpu.h>
-#include <linux/cpufreq.h>
-#include <linux/smp.h>
-#include <linux/sched/isolation.h>
#include <linux/rcupdate.h>
+#include <linux/sched/isolation.h>
+#include <linux/sched/topology.h>
+#include <linux/smp.h>
+#include <linux/syscore_ops.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>

#include "cpu.h"

@@ -152,3 +156,357 @@ unsigned int arch_freq_get_on_cpu(int cp

return per_cpu(samples.khz, cpu);
}
+
+#if defined(CONFIG_X86_64) && defined(CONFIG_SMP)
+/*
+ * APERF/MPERF frequency ratio computation.
+ *
+ * The scheduler wants to do frequency invariant accounting and needs a <1
+ * ratio to account for the 'current' frequency, corresponding to
+ * freq_curr / freq_max.
+ *
+ * Since the frequency freq_curr on x86 is controlled by micro-controller and
+ * our P-state setting is little more than a request/hint, we need to observe
+ * the effective frequency 'BusyMHz', i.e. the average frequency over a time
+ * interval after discarding idle time. This is given by:
+ *
+ * BusyMHz = delta_APERF / delta_MPERF * freq_base
+ *
+ * where freq_base is the max non-turbo P-state.
+ *
+ * The freq_max term has to be set to a somewhat arbitrary value, because we
+ * can't know which turbo states will be available at a given point in time:
+ * it all depends on the thermal headroom of the entire package. We set it to
+ * the turbo level with 4 cores active.
+ *
+ * Benchmarks show that's a good compromise between the 1C turbo ratio
+ * (freq_curr/freq_max would rarely reach 1) and something close to freq_base,
+ * which would ignore the entire turbo range (a conspicuous part, making
+ * freq_curr/freq_max always maxed out).
+ *
+ * An exception to the heuristic above is the Atom uarch, where we choose the
+ * highest turbo level for freq_max since Atom's are generally oriented towards
+ * power efficiency.
+ *
+ * Setting freq_max to anything less than the 1C turbo ratio makes the ratio
+ * freq_curr / freq_max to eventually grow >1, in which case we clip it to 1.
+ */
+
+DEFINE_STATIC_KEY_FALSE(arch_scale_freq_key);
+
+static DEFINE_PER_CPU(u64, arch_prev_aperf);
+static DEFINE_PER_CPU(u64, arch_prev_mperf);
+static u64 arch_turbo_freq_ratio = SCHED_CAPACITY_SCALE;
+static u64 arch_max_freq_ratio = SCHED_CAPACITY_SCALE;
+
+void arch_set_max_freq_ratio(bool turbo_disabled)
+{
+ arch_max_freq_ratio = turbo_disabled ? SCHED_CAPACITY_SCALE :
+ arch_turbo_freq_ratio;
+}
+EXPORT_SYMBOL_GPL(arch_set_max_freq_ratio);
+
+static bool turbo_disabled(void)
+{
+ u64 misc_en;
+ int err;
+
+ err = rdmsrl_safe(MSR_IA32_MISC_ENABLE, &misc_en);
+ if (err)
+ return false;
+
+ return (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
+}
+
+static bool slv_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
+{
+ int err;
+
+ err = rdmsrl_safe(MSR_ATOM_CORE_RATIOS, base_freq);
+ if (err)
+ return false;
+
+ err = rdmsrl_safe(MSR_ATOM_CORE_TURBO_RATIOS, turbo_freq);
+ if (err)
+ return false;
+
+ *base_freq = (*base_freq >> 16) & 0x3F; /* max P state */
+ *turbo_freq = *turbo_freq & 0x3F; /* 1C turbo */
+
+ return true;
+}
+
+#define X86_MATCH(model) \
+ X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6, \
+ INTEL_FAM6_##model, X86_FEATURE_APERFMPERF, NULL)
+
+static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
+ X86_MATCH(XEON_PHI_KNL),
+ X86_MATCH(XEON_PHI_KNM),
+ {}
+};
+
+static const struct x86_cpu_id has_skx_turbo_ratio_limits[] = {
+ X86_MATCH(SKYLAKE_X),
+ {}
+};
+
+static const struct x86_cpu_id has_glm_turbo_ratio_limits[] = {
+ X86_MATCH(ATOM_GOLDMONT),
+ X86_MATCH(ATOM_GOLDMONT_D),
+ X86_MATCH(ATOM_GOLDMONT_PLUS),
+ {}
+};
+
+static bool knl_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq,
+ int num_delta_fratio)
+{
+ int fratio, delta_fratio, found;
+ int err, i;
+ u64 msr;
+
+ err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
+ if (err)
+ return false;
+
+ *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
+
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
+ if (err)
+ return false;
+
+ fratio = (msr >> 8) & 0xFF;
+ i = 16;
+ found = 0;
+ do {
+ if (found >= num_delta_fratio) {
+ *turbo_freq = fratio;
+ return true;
+ }
+
+ delta_fratio = (msr >> (i + 5)) & 0x7;
+
+ if (delta_fratio) {
+ found += 1;
+ fratio -= delta_fratio;
+ }
+
+ i += 8;
+ } while (i < 64);
+
+ return true;
+}
+
+static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
+{
+ u64 ratios, counts;
+ u32 group_size;
+ int err, i;
+
+ err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
+ if (err)
+ return false;
+
+ *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
+
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &ratios);
+ if (err)
+ return false;
+
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT1, &counts);
+ if (err)
+ return false;
+
+ for (i = 0; i < 64; i += 8) {
+ group_size = (counts >> i) & 0xFF;
+ if (group_size >= size) {
+ *turbo_freq = (ratios >> i) & 0xFF;
+ return true;
+ }
+ }
+
+ return false;
+}
+
+static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
+{
+ u64 msr;
+ int err;
+
+ err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
+ if (err)
+ return false;
+
+ err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
+ if (err)
+ return false;
+
+ *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
+ *turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
+
+ /* The CPU may have less than 4 cores */
+ if (!*turbo_freq)
+ *turbo_freq = msr & 0xFF; /* 1C turbo */
+
+ return true;
+}
+
+static bool intel_set_max_freq_ratio(void)
+{
+ u64 base_freq, turbo_freq;
+ u64 turbo_ratio;
+
+ if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
+ goto out;
+
+ if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
+ skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
+ goto out;
+
+ if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
+ knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
+ goto out;
+
+ if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
+ skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
+ goto out;
+
+ if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
+ goto out;
+
+ return false;
+
+out:
+ /*
+ * Some hypervisors advertise X86_FEATURE_APERFMPERF
+ * but then fill all MSR's with zeroes.
+ * Some CPUs have turbo boost but don't declare any turbo ratio
+ * in MSR_TURBO_RATIO_LIMIT.
+ */
+ if (!base_freq || !turbo_freq) {
+ pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n");
+ return false;
+ }
+
+ turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
+ if (!turbo_ratio) {
+ pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
+ return false;
+ }
+
+ arch_turbo_freq_ratio = turbo_ratio;
+ arch_set_max_freq_ratio(turbo_disabled());
+
+ return true;
+}
+
+static void init_counter_refs(void)
+{
+ u64 aperf, mperf;
+
+ rdmsrl(MSR_IA32_APERF, aperf);
+ rdmsrl(MSR_IA32_MPERF, mperf);
+
+ this_cpu_write(arch_prev_aperf, aperf);
+ this_cpu_write(arch_prev_mperf, mperf);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static struct syscore_ops freq_invariance_syscore_ops = {
+ .resume = init_counter_refs,
+};
+
+static void register_freq_invariance_syscore_ops(void)
+{
+ /* Bail out if registered already. */
+ if (freq_invariance_syscore_ops.node.prev)
+ return;
+
+ register_syscore_ops(&freq_invariance_syscore_ops);
+}
+#else
+static inline void register_freq_invariance_syscore_ops(void) {}
+#endif
+
+void init_freq_invariance(bool secondary, bool cppc_ready)
+{
+ bool ret = false;
+
+ if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
+ return;
+
+ if (secondary) {
+ if (static_branch_likely(&arch_scale_freq_key)) {
+ init_counter_refs();
+ }
+ return;
+ }
+
+ if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+ ret = intel_set_max_freq_ratio();
+ else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
+ if (!cppc_ready) {
+ return;
+ }
+ ret = amd_set_max_freq_ratio(&arch_turbo_freq_ratio);
+ }
+
+ if (ret) {
+ init_counter_refs();
+ static_branch_enable(&arch_scale_freq_key);
+ register_freq_invariance_syscore_ops();
+ pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
+ } else {
+ pr_debug("Couldn't determine max cpu frequency, necessary for scale-invariant accounting.\n");
+ }
+}
+
+static void disable_freq_invariance_workfn(struct work_struct *work)
+{
+ static_branch_disable(&arch_scale_freq_key);
+}
+
+static DECLARE_WORK(disable_freq_invariance_work,
+ disable_freq_invariance_workfn);
+
+DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
+
+void arch_scale_freq_tick(void)
+{
+ u64 freq_scale;
+ u64 aperf, mperf;
+ u64 acnt, mcnt;
+
+ if (!arch_scale_freq_invariant())
+ return;
+
+ rdmsrl(MSR_IA32_APERF, aperf);
+ rdmsrl(MSR_IA32_MPERF, mperf);
+
+ acnt = aperf - this_cpu_read(arch_prev_aperf);
+ mcnt = mperf - this_cpu_read(arch_prev_mperf);
+
+ this_cpu_write(arch_prev_aperf, aperf);
+ this_cpu_write(arch_prev_mperf, mperf);
+
+ if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
+ goto error;
+
+ if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt)
+ goto error;
+
+ freq_scale = div64_u64(acnt, mcnt);
+ if (!freq_scale)
+ goto error;
+
+ if (freq_scale > SCHED_CAPACITY_SCALE)
+ freq_scale = SCHED_CAPACITY_SCALE;
+
+ this_cpu_write(arch_freq_scale, freq_scale);
+ return;
+
+error:
+ pr_warn("Scheduler frequency invariance went wobbly, disabling!\n");
+ schedule_work(&disable_freq_invariance_work);
+}
+#endif /* CONFIG_X86_64 && CONFIG_SMP */
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -56,7 +56,6 @@
#include <linux/numa.h>
#include <linux/pgtable.h>
#include <linux/overflow.h>
-#include <linux/syscore_ops.h>

#include <asm/acpi.h>
#include <asm/desc.h>
@@ -1847,357 +1846,3 @@ void native_play_dead(void)
}

#endif
-
-#ifdef CONFIG_X86_64
-/*
- * APERF/MPERF frequency ratio computation.
- *
- * The scheduler wants to do frequency invariant accounting and needs a <1
- * ratio to account for the 'current' frequency, corresponding to
- * freq_curr / freq_max.
- *
- * Since the frequency freq_curr on x86 is controlled by micro-controller and
- * our P-state setting is little more than a request/hint, we need to observe
- * the effective frequency 'BusyMHz', i.e. the average frequency over a time
- * interval after discarding idle time. This is given by:
- *
- * BusyMHz = delta_APERF / delta_MPERF * freq_base
- *
- * where freq_base is the max non-turbo P-state.
- *
- * The freq_max term has to be set to a somewhat arbitrary value, because we
- * can't know which turbo states will be available at a given point in time:
- * it all depends on the thermal headroom of the entire package. We set it to
- * the turbo level with 4 cores active.
- *
- * Benchmarks show that's a good compromise between the 1C turbo ratio
- * (freq_curr/freq_max would rarely reach 1) and something close to freq_base,
- * which would ignore the entire turbo range (a conspicuous part, making
- * freq_curr/freq_max always maxed out).
- *
- * An exception to the heuristic above is the Atom uarch, where we choose the
- * highest turbo level for freq_max since Atom's are generally oriented towards
- * power efficiency.
- *
- * Setting freq_max to anything less than the 1C turbo ratio makes the ratio
- * freq_curr / freq_max to eventually grow >1, in which case we clip it to 1.
- */
-
-DEFINE_STATIC_KEY_FALSE(arch_scale_freq_key);
-
-static DEFINE_PER_CPU(u64, arch_prev_aperf);
-static DEFINE_PER_CPU(u64, arch_prev_mperf);
-static u64 arch_turbo_freq_ratio = SCHED_CAPACITY_SCALE;
-static u64 arch_max_freq_ratio = SCHED_CAPACITY_SCALE;
-
-void arch_set_max_freq_ratio(bool turbo_disabled)
-{
- arch_max_freq_ratio = turbo_disabled ? SCHED_CAPACITY_SCALE :
- arch_turbo_freq_ratio;
-}
-EXPORT_SYMBOL_GPL(arch_set_max_freq_ratio);
-
-static bool turbo_disabled(void)
-{
- u64 misc_en;
- int err;
-
- err = rdmsrl_safe(MSR_IA32_MISC_ENABLE, &misc_en);
- if (err)
- return false;
-
- return (misc_en & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
-}
-
-static bool slv_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
-{
- int err;
-
- err = rdmsrl_safe(MSR_ATOM_CORE_RATIOS, base_freq);
- if (err)
- return false;
-
- err = rdmsrl_safe(MSR_ATOM_CORE_TURBO_RATIOS, turbo_freq);
- if (err)
- return false;
-
- *base_freq = (*base_freq >> 16) & 0x3F; /* max P state */
- *turbo_freq = *turbo_freq & 0x3F; /* 1C turbo */
-
- return true;
-}
-
-#define X86_MATCH(model) \
- X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 6, \
- INTEL_FAM6_##model, X86_FEATURE_APERFMPERF, NULL)
-
-static const struct x86_cpu_id has_knl_turbo_ratio_limits[] = {
- X86_MATCH(XEON_PHI_KNL),
- X86_MATCH(XEON_PHI_KNM),
- {}
-};
-
-static const struct x86_cpu_id has_skx_turbo_ratio_limits[] = {
- X86_MATCH(SKYLAKE_X),
- {}
-};
-
-static const struct x86_cpu_id has_glm_turbo_ratio_limits[] = {
- X86_MATCH(ATOM_GOLDMONT),
- X86_MATCH(ATOM_GOLDMONT_D),
- X86_MATCH(ATOM_GOLDMONT_PLUS),
- {}
-};
-
-static bool knl_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq,
- int num_delta_fratio)
-{
- int fratio, delta_fratio, found;
- int err, i;
- u64 msr;
-
- err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
- if (err)
- return false;
-
- *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
- if (err)
- return false;
-
- fratio = (msr >> 8) & 0xFF;
- i = 16;
- found = 0;
- do {
- if (found >= num_delta_fratio) {
- *turbo_freq = fratio;
- return true;
- }
-
- delta_fratio = (msr >> (i + 5)) & 0x7;
-
- if (delta_fratio) {
- found += 1;
- fratio -= delta_fratio;
- }
-
- i += 8;
- } while (i < 64);
-
- return true;
-}
-
-static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
-{
- u64 ratios, counts;
- u32 group_size;
- int err, i;
-
- err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
- if (err)
- return false;
-
- *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &ratios);
- if (err)
- return false;
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT1, &counts);
- if (err)
- return false;
-
- for (i = 0; i < 64; i += 8) {
- group_size = (counts >> i) & 0xFF;
- if (group_size >= size) {
- *turbo_freq = (ratios >> i) & 0xFF;
- return true;
- }
- }
-
- return false;
-}
-
-static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
-{
- u64 msr;
- int err;
-
- err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
- if (err)
- return false;
-
- err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
- if (err)
- return false;
-
- *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
- *turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
-
- /* The CPU may have less than 4 cores */
- if (!*turbo_freq)
- *turbo_freq = msr & 0xFF; /* 1C turbo */
-
- return true;
-}
-
-static bool intel_set_max_freq_ratio(void)
-{
- u64 base_freq, turbo_freq;
- u64 turbo_ratio;
-
- if (slv_set_max_freq_ratio(&base_freq, &turbo_freq))
- goto out;
-
- if (x86_match_cpu(has_glm_turbo_ratio_limits) &&
- skx_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
- goto out;
-
- if (x86_match_cpu(has_knl_turbo_ratio_limits) &&
- knl_set_max_freq_ratio(&base_freq, &turbo_freq, 1))
- goto out;
-
- if (x86_match_cpu(has_skx_turbo_ratio_limits) &&
- skx_set_max_freq_ratio(&base_freq, &turbo_freq, 4))
- goto out;
-
- if (core_set_max_freq_ratio(&base_freq, &turbo_freq))
- goto out;
-
- return false;
-
-out:
- /*
- * Some hypervisors advertise X86_FEATURE_APERFMPERF
- * but then fill all MSR's with zeroes.
- * Some CPUs have turbo boost but don't declare any turbo ratio
- * in MSR_TURBO_RATIO_LIMIT.
- */
- if (!base_freq || !turbo_freq) {
- pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n");
- return false;
- }
-
- turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq);
- if (!turbo_ratio) {
- pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n");
- return false;
- }
-
- arch_turbo_freq_ratio = turbo_ratio;
- arch_set_max_freq_ratio(turbo_disabled());
-
- return true;
-}
-
-static void init_counter_refs(void)
-{
- u64 aperf, mperf;
-
- rdmsrl(MSR_IA32_APERF, aperf);
- rdmsrl(MSR_IA32_MPERF, mperf);
-
- this_cpu_write(arch_prev_aperf, aperf);
- this_cpu_write(arch_prev_mperf, mperf);
-}
-
-#ifdef CONFIG_PM_SLEEP
-static struct syscore_ops freq_invariance_syscore_ops = {
- .resume = init_counter_refs,
-};
-
-static void register_freq_invariance_syscore_ops(void)
-{
- /* Bail out if registered already. */
- if (freq_invariance_syscore_ops.node.prev)
- return;
-
- register_syscore_ops(&freq_invariance_syscore_ops);
-}
-#else
-static inline void register_freq_invariance_syscore_ops(void) {}
-#endif
-
-void init_freq_invariance(bool secondary, bool cppc_ready)
-{
- bool ret = false;
-
- if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
- return;
-
- if (secondary) {
- if (static_branch_likely(&arch_scale_freq_key)) {
- init_counter_refs();
- }
- return;
- }
-
- if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
- ret = intel_set_max_freq_ratio();
- else if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
- if (!cppc_ready) {
- return;
- }
- ret = amd_set_max_freq_ratio(&arch_turbo_freq_ratio);
- }
-
- if (ret) {
- init_counter_refs();
- static_branch_enable(&arch_scale_freq_key);
- register_freq_invariance_syscore_ops();
- pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
- } else {
- pr_debug("Couldn't determine max cpu frequency, necessary for scale-invariant accounting.\n");
- }
-}
-
-static void disable_freq_invariance_workfn(struct work_struct *work)
-{
- static_branch_disable(&arch_scale_freq_key);
-}
-
-static DECLARE_WORK(disable_freq_invariance_work,
- disable_freq_invariance_workfn);
-
-DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE;
-
-void arch_scale_freq_tick(void)
-{
- u64 freq_scale;
- u64 aperf, mperf;
- u64 acnt, mcnt;
-
- if (!arch_scale_freq_invariant())
- return;
-
- rdmsrl(MSR_IA32_APERF, aperf);
- rdmsrl(MSR_IA32_MPERF, mperf);
-
- acnt = aperf - this_cpu_read(arch_prev_aperf);
- mcnt = mperf - this_cpu_read(arch_prev_mperf);
-
- this_cpu_write(arch_prev_aperf, aperf);
- this_cpu_write(arch_prev_mperf, mperf);
-
- if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt))
- goto error;
-
- if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt)
- goto error;
-
- freq_scale = div64_u64(acnt, mcnt);
- if (!freq_scale)
- goto error;
-
- if (freq_scale > SCHED_CAPACITY_SCALE)
- freq_scale = SCHED_CAPACITY_SCALE;
-
- this_cpu_write(arch_freq_scale, freq_scale);
- return;
-
-error:
- pr_warn("Scheduler frequency invariance went wobbly, disabling!\n");
- schedule_work(&disable_freq_invariance_work);
-}
-#endif /* CONFIG_X86_64 */