From 9e35ad388bea89f7d6f375af4c0ae98803688666 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 13 May 2009 16:21:38 +0200 Subject: [PATCH] perf_counter: Rework the perf counter disable/enable The current disable/enable mechanism is: token = hw_perf_save_disable(); ... /* do bits */ ... hw_perf_restore(token); This works well, provided that the use nests properly. Except we don't. x86 NMI/INT throttling has non-nested use of this, breaking things. Therefore provide a reference counter disable/enable interface, where the first disable disables the hardware, and the last enable enables the hardware again. [ Impact: refactor, simplify the PMU disable/enable logic ] Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Corey Ashford LKML-Reference: Signed-off-by: Ingo Molnar --- arch/powerpc/kernel/perf_counter.c | 24 +++--- arch/x86/kernel/cpu/perf_counter.c | 113 +++++++++++------------------ drivers/acpi/processor_idle.c | 6 +- include/linux/perf_counter.h | 10 ++- kernel/perf_counter.c | 76 +++++++++++-------- 5 files changed, 109 insertions(+), 120 deletions(-) diff --git a/arch/powerpc/kernel/perf_counter.c b/arch/powerpc/kernel/perf_counter.c index 15cdc8e67229..bb1b463c1361 100644 --- a/arch/powerpc/kernel/perf_counter.c +++ b/arch/powerpc/kernel/perf_counter.c @@ -386,7 +386,7 @@ static void write_mmcr0(struct cpu_hw_counters *cpuhw, unsigned long mmcr0) * Disable all counters to prevent PMU interrupts and to allow * counters to be added or removed. */ -u64 hw_perf_save_disable(void) +void hw_perf_disable(void) { struct cpu_hw_counters *cpuhw; unsigned long ret; @@ -428,7 +428,6 @@ u64 hw_perf_save_disable(void) mb(); } local_irq_restore(flags); - return ret; } /* @@ -436,7 +435,7 @@ u64 hw_perf_save_disable(void) * If we were previously disabled and counters were added, then * put the new config on the PMU. */ -void hw_perf_restore(u64 disable) +void hw_perf_enable(void) { struct perf_counter *counter; struct cpu_hw_counters *cpuhw; @@ -448,9 +447,12 @@ void hw_perf_restore(u64 disable) int n_lim; int idx; - if (disable) - return; local_irq_save(flags); + if (!cpuhw->disabled) { + local_irq_restore(flags); + return; + } + cpuhw = &__get_cpu_var(cpu_hw_counters); cpuhw->disabled = 0; @@ -649,19 +651,18 @@ int hw_perf_group_sched_in(struct perf_counter *group_leader, /* * Add a counter to the PMU. * If all counters are not already frozen, then we disable and - * re-enable the PMU in order to get hw_perf_restore to do the + * re-enable the PMU in order to get hw_perf_enable to do the * actual work of reconfiguring the PMU. */ static int power_pmu_enable(struct perf_counter *counter) { struct cpu_hw_counters *cpuhw; unsigned long flags; - u64 pmudis; int n0; int ret = -EAGAIN; local_irq_save(flags); - pmudis = hw_perf_save_disable(); + perf_disable(); /* * Add the counter to the list (if there is room) @@ -685,7 +686,7 @@ static int power_pmu_enable(struct perf_counter *counter) ret = 0; out: - hw_perf_restore(pmudis); + perf_enable(); local_irq_restore(flags); return ret; } @@ -697,11 +698,10 @@ static void power_pmu_disable(struct perf_counter *counter) { struct cpu_hw_counters *cpuhw; long i; - u64 pmudis; unsigned long flags; local_irq_save(flags); - pmudis = hw_perf_save_disable(); + perf_disable(); power_pmu_read(counter); @@ -735,7 +735,7 @@ static void power_pmu_disable(struct perf_counter *counter) cpuhw->mmcr[0] &= ~(MMCR0_PMXE | MMCR0_FCECE); } - hw_perf_restore(pmudis); + perf_enable(); local_irq_restore(flags); } diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 7601c014f8f6..313638cecbb5 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -31,7 +31,6 @@ struct cpu_hw_counters { unsigned long used_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)]; unsigned long active_mask[BITS_TO_LONGS(X86_PMC_IDX_MAX)]; unsigned long interrupts; - u64 throttle_ctrl; int enabled; }; @@ -42,8 +41,8 @@ struct x86_pmu { const char *name; int version; int (*handle_irq)(struct pt_regs *, int); - u64 (*save_disable_all)(void); - void (*restore_all)(u64); + void (*disable_all)(void); + void (*enable_all)(void); void (*enable)(struct hw_perf_counter *, int); void (*disable)(struct hw_perf_counter *, int); unsigned eventsel; @@ -56,6 +55,7 @@ struct x86_pmu { int counter_bits; u64 counter_mask; u64 max_period; + u64 intel_ctrl; }; static struct x86_pmu x86_pmu __read_mostly; @@ -311,22 +311,19 @@ static int __hw_perf_counter_init(struct perf_counter *counter) return 0; } -static u64 intel_pmu_save_disable_all(void) +static void intel_pmu_disable_all(void) { - u64 ctrl; - - rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl); wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, 0); - - return ctrl; } -static u64 amd_pmu_save_disable_all(void) +static void amd_pmu_disable_all(void) { struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters); - int enabled, idx; + int idx; + + if (!cpuc->enabled) + return; - enabled = cpuc->enabled; cpuc->enabled = 0; /* * ensure we write the disable before we start disabling the @@ -334,8 +331,6 @@ static u64 amd_pmu_save_disable_all(void) * right thing. */ barrier(); - if (!enabled) - goto out; for (idx = 0; idx < x86_pmu.num_counters; idx++) { u64 val; @@ -348,37 +343,31 @@ static u64 amd_pmu_save_disable_all(void) val &= ~ARCH_PERFMON_EVENTSEL0_ENABLE; wrmsrl(MSR_K7_EVNTSEL0 + idx, val); } - -out: - return enabled; } -u64 hw_perf_save_disable(void) +void hw_perf_disable(void) { if (!x86_pmu_initialized()) - return 0; - return x86_pmu.save_disable_all(); + return; + return x86_pmu.disable_all(); } -/* - * Exported because of ACPI idle - */ -EXPORT_SYMBOL_GPL(hw_perf_save_disable); -static void intel_pmu_restore_all(u64 ctrl) +static void intel_pmu_enable_all(void) { - wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl); + wrmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl); } -static void amd_pmu_restore_all(u64 ctrl) +static void amd_pmu_enable_all(void) { struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters); int idx; - cpuc->enabled = ctrl; - barrier(); - if (!ctrl) + if (cpuc->enabled) return; + cpuc->enabled = 1; + barrier(); + for (idx = 0; idx < x86_pmu.num_counters; idx++) { u64 val; @@ -392,16 +381,12 @@ static void amd_pmu_restore_all(u64 ctrl) } } -void hw_perf_restore(u64 ctrl) +void hw_perf_enable(void) { if (!x86_pmu_initialized()) return; - x86_pmu.restore_all(ctrl); + x86_pmu.enable_all(); } -/* - * Exported because of ACPI idle - */ -EXPORT_SYMBOL_GPL(hw_perf_restore); static inline u64 intel_pmu_get_status(void) { @@ -735,15 +720,14 @@ static int intel_pmu_handle_irq(struct pt_regs *regs, int nmi) int bit, cpu = smp_processor_id(); u64 ack, status; struct cpu_hw_counters *cpuc = &per_cpu(cpu_hw_counters, cpu); - int ret = 0; - - cpuc->throttle_ctrl = intel_pmu_save_disable_all(); + perf_disable(); status = intel_pmu_get_status(); - if (!status) - goto out; + if (!status) { + perf_enable(); + return 0; + } - ret = 1; again: inc_irq_stat(apic_perf_irqs); ack = status; @@ -767,19 +751,11 @@ again: status = intel_pmu_get_status(); if (status) goto again; -out: - /* - * Restore - do not reenable when global enable is off or throttled: - */ - if (cpuc->throttle_ctrl) { - if (++cpuc->interrupts < PERFMON_MAX_INTERRUPTS) { - intel_pmu_restore_all(cpuc->throttle_ctrl); - } else { - pr_info("CPU#%d: perfcounters: max interrupt rate exceeded! Throttle on.\n", smp_processor_id()); - } - } - return ret; + if (++cpuc->interrupts != PERFMON_MAX_INTERRUPTS) + perf_enable(); + + return 1; } static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi) @@ -792,13 +768,11 @@ static int amd_pmu_handle_irq(struct pt_regs *regs, int nmi) struct hw_perf_counter *hwc; int idx, throttle = 0; - cpuc->throttle_ctrl = cpuc->enabled; - cpuc->enabled = 0; - barrier(); - - if (cpuc->throttle_ctrl) { - if (++cpuc->interrupts >= PERFMON_MAX_INTERRUPTS) - throttle = 1; + if (++cpuc->interrupts == PERFMON_MAX_INTERRUPTS) { + throttle = 1; + __perf_disable(); + cpuc->enabled = 0; + barrier(); } for (idx = 0; idx < x86_pmu.num_counters; idx++) { @@ -824,9 +798,6 @@ next: amd_pmu_disable_counter(hwc, idx); } - if (cpuc->throttle_ctrl && !throttle) - cpuc->enabled = 1; - return handled; } @@ -839,13 +810,11 @@ void perf_counter_unthrottle(void) cpuc = &__get_cpu_var(cpu_hw_counters); if (cpuc->interrupts >= PERFMON_MAX_INTERRUPTS) { - pr_info("CPU#%d: perfcounters: throttle off.\n", smp_processor_id()); - /* * Clear them before re-enabling irqs/NMIs again: */ cpuc->interrupts = 0; - hw_perf_restore(cpuc->throttle_ctrl); + perf_enable(); } else { cpuc->interrupts = 0; } @@ -931,8 +900,8 @@ static __read_mostly struct notifier_block perf_counter_nmi_notifier = { static struct x86_pmu intel_pmu = { .name = "Intel", .handle_irq = intel_pmu_handle_irq, - .save_disable_all = intel_pmu_save_disable_all, - .restore_all = intel_pmu_restore_all, + .disable_all = intel_pmu_disable_all, + .enable_all = intel_pmu_enable_all, .enable = intel_pmu_enable_counter, .disable = intel_pmu_disable_counter, .eventsel = MSR_ARCH_PERFMON_EVENTSEL0, @@ -951,8 +920,8 @@ static struct x86_pmu intel_pmu = { static struct x86_pmu amd_pmu = { .name = "AMD", .handle_irq = amd_pmu_handle_irq, - .save_disable_all = amd_pmu_save_disable_all, - .restore_all = amd_pmu_restore_all, + .disable_all = amd_pmu_disable_all, + .enable_all = amd_pmu_enable_all, .enable = amd_pmu_enable_counter, .disable = amd_pmu_disable_counter, .eventsel = MSR_K7_EVNTSEL0, @@ -1003,6 +972,8 @@ static int intel_pmu_init(void) x86_pmu.counter_bits = eax.split.bit_width; x86_pmu.counter_mask = (1ULL << eax.split.bit_width) - 1; + rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, x86_pmu.intel_ctrl); + return 0; } diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index d2830f39d46b..9645758c0472 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -763,11 +763,9 @@ static int acpi_idle_bm_check(void) */ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx) { - u64 perf_flags; - /* Don't trace irqs off for idle */ stop_critical_timings(); - perf_flags = hw_perf_save_disable(); + perf_disable(); if (cx->entry_method == ACPI_CSTATE_FFH) { /* Call into architectural FFH based C-state */ acpi_processor_ffh_cstate_enter(cx); @@ -782,7 +780,7 @@ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx) gets asserted in time to freeze execution properly. */ unused = inl(acpi_gbl_FADT.xpm_timer_block.address); } - hw_perf_restore(perf_flags); + perf_enable(); start_critical_timings(); } diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index 614f921d616a..e543ecc129f1 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -544,8 +544,10 @@ extern void perf_counter_exit_task(struct task_struct *child); extern void perf_counter_do_pending(void); extern void perf_counter_print_debug(void); extern void perf_counter_unthrottle(void); -extern u64 hw_perf_save_disable(void); -extern void hw_perf_restore(u64 ctrl); +extern void __perf_disable(void); +extern bool __perf_enable(void); +extern void perf_disable(void); +extern void perf_enable(void); extern int perf_counter_task_disable(void); extern int perf_counter_task_enable(void); extern int hw_perf_group_sched_in(struct perf_counter *group_leader, @@ -600,8 +602,8 @@ static inline void perf_counter_exit_task(struct task_struct *child) { } static inline void perf_counter_do_pending(void) { } static inline void perf_counter_print_debug(void) { } static inline void perf_counter_unthrottle(void) { } -static inline void hw_perf_restore(u64 ctrl) { } -static inline u64 hw_perf_save_disable(void) { return 0; } +static inline void perf_disable(void) { } +static inline void perf_enable(void) { } static inline int perf_counter_task_disable(void) { return -EINVAL; } static inline int perf_counter_task_enable(void) { return -EINVAL; } diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 985be0b662af..e814ff04d7ca 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -60,8 +60,9 @@ extern __weak const struct pmu *hw_perf_counter_init(struct perf_counter *counte return NULL; } -u64 __weak hw_perf_save_disable(void) { return 0; } -void __weak hw_perf_restore(u64 ctrl) { barrier(); } +void __weak hw_perf_disable(void) { barrier(); } +void __weak hw_perf_enable(void) { barrier(); } + void __weak hw_perf_counter_setup(int cpu) { barrier(); } int __weak hw_perf_group_sched_in(struct perf_counter *group_leader, struct perf_cpu_context *cpuctx, @@ -72,6 +73,32 @@ int __weak hw_perf_group_sched_in(struct perf_counter *group_leader, void __weak perf_counter_print_debug(void) { } +static DEFINE_PER_CPU(int, disable_count); + +void __perf_disable(void) +{ + __get_cpu_var(disable_count)++; +} + +bool __perf_enable(void) +{ + return !--__get_cpu_var(disable_count); +} + +void perf_disable(void) +{ + __perf_disable(); + hw_perf_disable(); +} +EXPORT_SYMBOL_GPL(perf_disable); /* ACPI idle */ + +void perf_enable(void) +{ + if (__perf_enable()) + hw_perf_enable(); +} +EXPORT_SYMBOL_GPL(perf_enable); /* ACPI idle */ + static void list_add_counter(struct perf_counter *counter, struct perf_counter_context *ctx) { @@ -170,7 +197,6 @@ static void __perf_counter_remove_from_context(void *info) struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; unsigned long flags; - u64 perf_flags; /* * If this is a task context, we need to check whether it is @@ -191,9 +217,9 @@ static void __perf_counter_remove_from_context(void *info) * Protect the list operation against NMI by disabling the * counters on a global level. NOP for non NMI based counters. */ - perf_flags = hw_perf_save_disable(); + perf_disable(); list_del_counter(counter, ctx); - hw_perf_restore(perf_flags); + perf_enable(); if (!ctx->task) { /* @@ -538,7 +564,6 @@ static void __perf_install_in_context(void *info) struct perf_counter *leader = counter->group_leader; int cpu = smp_processor_id(); unsigned long flags; - u64 perf_flags; int err; /* @@ -556,7 +581,7 @@ static void __perf_install_in_context(void *info) * Protect the list operation against NMI by disabling the * counters on a global level. NOP for non NMI based counters. */ - perf_flags = hw_perf_save_disable(); + perf_disable(); add_counter_to_ctx(counter, ctx); @@ -596,7 +621,7 @@ static void __perf_install_in_context(void *info) cpuctx->max_pertask--; unlock: - hw_perf_restore(perf_flags); + perf_enable(); spin_unlock_irqrestore(&ctx->lock, flags); } @@ -663,7 +688,6 @@ static void __perf_counter_enable(void *info) struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter_context *ctx = counter->ctx; struct perf_counter *leader = counter->group_leader; - unsigned long pmuflags; unsigned long flags; int err; @@ -693,14 +717,14 @@ static void __perf_counter_enable(void *info) if (!group_can_go_on(counter, cpuctx, 1)) { err = -EEXIST; } else { - pmuflags = hw_perf_save_disable(); + perf_disable(); if (counter == leader) err = group_sched_in(counter, cpuctx, ctx, smp_processor_id()); else err = counter_sched_in(counter, cpuctx, ctx, smp_processor_id()); - hw_perf_restore(pmuflags); + perf_enable(); } if (err) { @@ -795,7 +819,6 @@ void __perf_counter_sched_out(struct perf_counter_context *ctx, struct perf_cpu_context *cpuctx) { struct perf_counter *counter; - u64 flags; spin_lock(&ctx->lock); ctx->is_active = 0; @@ -803,12 +826,12 @@ void __perf_counter_sched_out(struct perf_counter_context *ctx, goto out; update_context_time(ctx); - flags = hw_perf_save_disable(); + perf_disable(); if (ctx->nr_active) { list_for_each_entry(counter, &ctx->counter_list, list_entry) group_sched_out(counter, cpuctx, ctx); } - hw_perf_restore(flags); + perf_enable(); out: spin_unlock(&ctx->lock); } @@ -860,7 +883,6 @@ __perf_counter_sched_in(struct perf_counter_context *ctx, struct perf_cpu_context *cpuctx, int cpu) { struct perf_counter *counter; - u64 flags; int can_add_hw = 1; spin_lock(&ctx->lock); @@ -870,7 +892,7 @@ __perf_counter_sched_in(struct perf_counter_context *ctx, ctx->timestamp = perf_clock(); - flags = hw_perf_save_disable(); + perf_disable(); /* * First go through the list and put on any pinned groups @@ -917,7 +939,7 @@ __perf_counter_sched_in(struct perf_counter_context *ctx, can_add_hw = 0; } } - hw_perf_restore(flags); + perf_enable(); out: spin_unlock(&ctx->lock); } @@ -955,7 +977,6 @@ int perf_counter_task_disable(void) struct perf_counter_context *ctx = &curr->perf_counter_ctx; struct perf_counter *counter; unsigned long flags; - u64 perf_flags; if (likely(!ctx->nr_counters)) return 0; @@ -969,7 +990,7 @@ int perf_counter_task_disable(void) /* * Disable all the counters: */ - perf_flags = hw_perf_save_disable(); + perf_disable(); list_for_each_entry(counter, &ctx->counter_list, list_entry) { if (counter->state != PERF_COUNTER_STATE_ERROR) { @@ -978,7 +999,7 @@ int perf_counter_task_disable(void) } } - hw_perf_restore(perf_flags); + perf_enable(); spin_unlock_irqrestore(&ctx->lock, flags); @@ -991,7 +1012,6 @@ int perf_counter_task_enable(void) struct perf_counter_context *ctx = &curr->perf_counter_ctx; struct perf_counter *counter; unsigned long flags; - u64 perf_flags; int cpu; if (likely(!ctx->nr_counters)) @@ -1007,7 +1027,7 @@ int perf_counter_task_enable(void) /* * Disable all the counters: */ - perf_flags = hw_perf_save_disable(); + perf_disable(); list_for_each_entry(counter, &ctx->counter_list, list_entry) { if (counter->state > PERF_COUNTER_STATE_OFF) @@ -1017,7 +1037,7 @@ int perf_counter_task_enable(void) ctx->time - counter->total_time_enabled; counter->hw_event.disabled = 0; } - hw_perf_restore(perf_flags); + perf_enable(); spin_unlock(&ctx->lock); @@ -1034,7 +1054,6 @@ int perf_counter_task_enable(void) static void rotate_ctx(struct perf_counter_context *ctx) { struct perf_counter *counter; - u64 perf_flags; if (!ctx->nr_counters) return; @@ -1043,12 +1062,12 @@ static void rotate_ctx(struct perf_counter_context *ctx) /* * Rotate the first entry last (works just fine for group counters too): */ - perf_flags = hw_perf_save_disable(); + perf_disable(); list_for_each_entry(counter, &ctx->counter_list, list_entry) { list_move_tail(&counter->list_entry, &ctx->counter_list); break; } - hw_perf_restore(perf_flags); + perf_enable(); spin_unlock(&ctx->lock); } @@ -3194,7 +3213,6 @@ __perf_counter_exit_task(struct task_struct *child, } else { struct perf_cpu_context *cpuctx; unsigned long flags; - u64 perf_flags; /* * Disable and unlink this counter. @@ -3203,7 +3221,7 @@ __perf_counter_exit_task(struct task_struct *child, * could still be processing it: */ local_irq_save(flags); - perf_flags = hw_perf_save_disable(); + perf_disable(); cpuctx = &__get_cpu_var(perf_cpu_context); @@ -3214,7 +3232,7 @@ __perf_counter_exit_task(struct task_struct *child, child_ctx->nr_counters--; - hw_perf_restore(perf_flags); + perf_enable(); local_irq_restore(flags); }