From 2f18d1e8d07ae67dd0afce875287756d4bd31a46 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 22 Dec 2008 11:10:42 +0100 Subject: [PATCH] x86, perfcounters: add support for fixed-function pmcs Impact: extend performance counter support on x86 Intel CPUs Modern Intel CPUs have 3 "fixed-function" performance counters, which count these hardware events: Instr_Retired.Any CPU_CLK_Unhalted.Core CPU_CLK_Unhalted.Ref Add support for them to the performance counters subsystem. Their use is transparent to user-space: the counter scheduler is extended to automatically recognize the cases where a fixed-function PMC can be utilized instead of a generic PMC. In such cases the generic PMC is kept available for more counters. The above fixed-function events map to these generic counter hw events: PERF_COUNT_INSTRUCTIONS PERF_COUNT_CPU_CYCLES PERF_COUNT_BUS_CYCLES (The 'bus' cycles are in reality often CPU-ish cycles, just with a fixed frequency.) Signed-off-by: Ingo Molnar --- arch/x86/include/asm/perf_counter.h | 8 ++ arch/x86/kernel/cpu/perf_counter.c | 149 +++++++++++++++++++++++----- 2 files changed, 133 insertions(+), 24 deletions(-) diff --git a/arch/x86/include/asm/perf_counter.h b/arch/x86/include/asm/perf_counter.h index 13745deb16c..2e08ed73664 100644 --- a/arch/x86/include/asm/perf_counter.h +++ b/arch/x86/include/asm/perf_counter.h @@ -23,6 +23,11 @@ #define ARCH_PERFMON_EVENTSEL_OS (1 << 17) #define ARCH_PERFMON_EVENTSEL_USR (1 << 16) +/* + * Includes eventsel and unit mask as well: + */ +#define ARCH_PERFMON_EVENT_MASK 0xffff + #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL 0x3c #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK (0x00 << 8) #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX 0 @@ -69,12 +74,15 @@ union cpuid10_edx { /* Instr_Retired.Any: */ #define MSR_ARCH_PERFMON_FIXED_CTR0 0x309 +#define X86_PMC_IDX_FIXED_INSTRUCTIONS (X86_PMC_IDX_FIXED + 0) /* CPU_CLK_Unhalted.Core: */ #define MSR_ARCH_PERFMON_FIXED_CTR1 0x30a +#define X86_PMC_IDX_FIXED_CPU_CYCLES (X86_PMC_IDX_FIXED + 1) /* CPU_CLK_Unhalted.Ref: */ #define MSR_ARCH_PERFMON_FIXED_CTR2 0x30b +#define X86_PMC_IDX_FIXED_BUS_CYCLES (X86_PMC_IDX_FIXED + 2) #ifdef CONFIG_PERF_COUNTERS extern void init_hw_perf_counters(void); diff --git a/arch/x86/kernel/cpu/perf_counter.c b/arch/x86/kernel/cpu/perf_counter.c index 86b2fdd344a..da46eca1254 100644 --- a/arch/x86/kernel/cpu/perf_counter.c +++ b/arch/x86/kernel/cpu/perf_counter.c @@ -26,6 +26,7 @@ static bool perf_counters_initialized __read_mostly; */ static int nr_counters_generic __read_mostly; static u64 perf_counter_mask __read_mostly; +static u64 counter_value_mask __read_mostly; static int nr_counters_fixed __read_mostly; @@ -120,9 +121,6 @@ static int __hw_perf_counter_init(struct perf_counter *counter) hwc->nmi = 1; } - hwc->config_base = MSR_ARCH_PERFMON_EVENTSEL0; - hwc->counter_base = MSR_ARCH_PERFMON_PERFCTR0; - hwc->irq_period = hw_event->irq_period; /* * Intel PMCs cannot be accessed sanely above 32 bit width, @@ -183,16 +181,34 @@ void hw_perf_restore(u64 ctrl) } EXPORT_SYMBOL_GPL(hw_perf_restore); +static inline void +__pmc_fixed_disable(struct perf_counter *counter, + struct hw_perf_counter *hwc, unsigned int __idx) +{ + int idx = __idx - X86_PMC_IDX_FIXED; + u64 ctrl_val, mask; + int err; + + mask = 0xfULL << (idx * 4); + + rdmsrl(hwc->config_base, ctrl_val); + ctrl_val &= ~mask; + err = checking_wrmsrl(hwc->config_base, ctrl_val); +} + static inline void __pmc_generic_disable(struct perf_counter *counter, struct hw_perf_counter *hwc, unsigned int idx) { int err; + if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) + return __pmc_fixed_disable(counter, hwc, idx); + err = wrmsr_safe(hwc->config_base + idx, hwc->config, 0); } -static DEFINE_PER_CPU(u64, prev_left[X86_PMC_MAX_GENERIC]); +static DEFINE_PER_CPU(u64, prev_left[X86_PMC_IDX_MAX]); /* * Set the next IRQ period, based on the hwc->period_left value. @@ -202,8 +218,9 @@ static void __hw_perf_counter_set_period(struct perf_counter *counter, struct hw_perf_counter *hwc, int idx) { - s32 left = atomic64_read(&hwc->period_left); + s64 left = atomic64_read(&hwc->period_left); s32 period = hwc->irq_period; + int err; /* * If we are way outside a reasoable range then just skip forward: @@ -224,21 +241,64 @@ __hw_perf_counter_set_period(struct perf_counter *counter, * The hw counter starts counting from this counter offset, * mark it to be able to extra future deltas: */ - atomic64_set(&hwc->prev_count, (u64)(s64)-left); + atomic64_set(&hwc->prev_count, (u64)-left); - wrmsr(hwc->counter_base + idx, -left, 0); + err = checking_wrmsrl(hwc->counter_base + idx, + (u64)(-left) & counter_value_mask); +} + +static inline void +__pmc_fixed_enable(struct perf_counter *counter, + struct hw_perf_counter *hwc, unsigned int __idx) +{ + int idx = __idx - X86_PMC_IDX_FIXED; + u64 ctrl_val, bits, mask; + int err; + + /* + * Enable IRQ generation (0x8) and ring-3 counting (0x2), + * and enable ring-0 counting if allowed: + */ + bits = 0x8ULL | 0x2ULL; + if (hwc->config & ARCH_PERFMON_EVENTSEL_OS) + bits |= 0x1; + bits <<= (idx * 4); + mask = 0xfULL << (idx * 4); + + rdmsrl(hwc->config_base, ctrl_val); + ctrl_val &= ~mask; + ctrl_val |= bits; + err = checking_wrmsrl(hwc->config_base, ctrl_val); } static void __pmc_generic_enable(struct perf_counter *counter, struct hw_perf_counter *hwc, int idx) { + if (unlikely(hwc->config_base == MSR_ARCH_PERFMON_FIXED_CTR_CTRL)) + return __pmc_fixed_enable(counter, hwc, idx); + wrmsr(hwc->config_base + idx, hwc->config | ARCH_PERFMON_EVENTSEL0_ENABLE, 0); } -static int fixed_mode_idx(struct hw_perf_counter *hwc) +static int +fixed_mode_idx(struct perf_counter *counter, struct hw_perf_counter *hwc) { + unsigned int event; + + if (unlikely(hwc->nmi)) + return -1; + + event = hwc->config & ARCH_PERFMON_EVENT_MASK; + + if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_INSTRUCTIONS])) + return X86_PMC_IDX_FIXED_INSTRUCTIONS; + if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_CPU_CYCLES])) + return X86_PMC_IDX_FIXED_CPU_CYCLES; + if (unlikely(event == intel_perfmon_event_map[PERF_COUNT_BUS_CYCLES])) + return X86_PMC_IDX_FIXED_BUS_CYCLES; + return -1; } @@ -249,16 +309,39 @@ static int pmc_generic_enable(struct perf_counter *counter) { struct cpu_hw_counters *cpuc = &__get_cpu_var(cpu_hw_counters); struct hw_perf_counter *hwc = &counter->hw; - int idx = hwc->idx; + int idx; - /* Try to get the previous counter again */ - if (test_and_set_bit(idx, cpuc->used)) { - idx = find_first_zero_bit(cpuc->used, nr_counters_generic); - if (idx == nr_counters_generic) - return -EAGAIN; + idx = fixed_mode_idx(counter, hwc); + if (idx >= 0) { + /* + * Try to get the fixed counter, if that is already taken + * then try to get a generic counter: + */ + if (test_and_set_bit(idx, cpuc->used)) + goto try_generic; - set_bit(idx, cpuc->used); + hwc->config_base = MSR_ARCH_PERFMON_FIXED_CTR_CTRL; + /* + * We set it so that counter_base + idx in wrmsr/rdmsr maps to + * MSR_ARCH_PERFMON_FIXED_CTR0 ... CTR2: + */ + hwc->counter_base = + MSR_ARCH_PERFMON_FIXED_CTR0 - X86_PMC_IDX_FIXED; hwc->idx = idx; + } else { + idx = hwc->idx; + /* Try to get the previous generic counter again */ + if (test_and_set_bit(idx, cpuc->used)) { +try_generic: + idx = find_first_zero_bit(cpuc->used, nr_counters_generic); + if (idx == nr_counters_generic) + return -EAGAIN; + + set_bit(idx, cpuc->used); + hwc->idx = idx; + } + hwc->config_base = MSR_ARCH_PERFMON_EVENTSEL0; + hwc->counter_base = MSR_ARCH_PERFMON_PERFCTR0; } perf_counters_lapic_init(hwc->nmi); @@ -266,6 +349,10 @@ static int pmc_generic_enable(struct perf_counter *counter) __pmc_generic_disable(counter, hwc, idx); cpuc->counters[idx] = counter; + /* + * Make it visible before enabling the hw: + */ + smp_wmb(); __hw_perf_counter_set_period(counter, hwc, idx); __pmc_generic_enable(counter, hwc, idx); @@ -275,7 +362,7 @@ static int pmc_generic_enable(struct perf_counter *counter) void perf_counter_print_debug(void) { - u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left; + u64 ctrl, status, overflow, pmc_ctrl, pmc_count, prev_left, fixed; struct cpu_hw_counters *cpuc; int cpu, idx; @@ -290,11 +377,13 @@ void perf_counter_print_debug(void) rdmsrl(MSR_CORE_PERF_GLOBAL_CTRL, ctrl); rdmsrl(MSR_CORE_PERF_GLOBAL_STATUS, status); rdmsrl(MSR_CORE_PERF_GLOBAL_OVF_CTRL, overflow); + rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR_CTRL, fixed); printk(KERN_INFO "\n"); printk(KERN_INFO "CPU#%d: ctrl: %016llx\n", cpu, ctrl); printk(KERN_INFO "CPU#%d: status: %016llx\n", cpu, status); printk(KERN_INFO "CPU#%d: overflow: %016llx\n", cpu, overflow); + printk(KERN_INFO "CPU#%d: fixed: %016llx\n", cpu, fixed); printk(KERN_INFO "CPU#%d: used: %016llx\n", cpu, *(u64 *)cpuc->used); for (idx = 0; idx < nr_counters_generic; idx++) { @@ -303,13 +392,19 @@ void perf_counter_print_debug(void) prev_left = per_cpu(prev_left[idx], cpu); - printk(KERN_INFO "CPU#%d: PMC%d ctrl: %016llx\n", + printk(KERN_INFO "CPU#%d: gen-PMC%d ctrl: %016llx\n", cpu, idx, pmc_ctrl); - printk(KERN_INFO "CPU#%d: PMC%d count: %016llx\n", + printk(KERN_INFO "CPU#%d: gen-PMC%d count: %016llx\n", cpu, idx, pmc_count); - printk(KERN_INFO "CPU#%d: PMC%d left: %016llx\n", + printk(KERN_INFO "CPU#%d: gen-PMC%d left: %016llx\n", cpu, idx, prev_left); } + for (idx = 0; idx < nr_counters_fixed; idx++) { + rdmsrl(MSR_ARCH_PERFMON_FIXED_CTR0 + idx, pmc_count); + + printk(KERN_INFO "CPU#%d: fixed-PMC%d count: %016llx\n", + cpu, idx, pmc_count); + } local_irq_enable(); } @@ -323,6 +418,11 @@ static void pmc_generic_disable(struct perf_counter *counter) clear_bit(idx, cpuc->used); cpuc->counters[idx] = NULL; + /* + * Make sure the cleared pointer becomes visible before we + * (potentially) free the counter: + */ + smp_wmb(); /* * Drain the remaining delta count out of a counter @@ -353,14 +453,11 @@ static void perf_save_and_restart(struct perf_counter *counter) { struct hw_perf_counter *hwc = &counter->hw; int idx = hwc->idx; - u64 pmc_ctrl; - - rdmsrl(MSR_ARCH_PERFMON_EVENTSEL0 + idx, pmc_ctrl); x86_perf_counter_update(counter, hwc, idx); __hw_perf_counter_set_period(counter, hwc, idx); - if (pmc_ctrl & ARCH_PERFMON_EVENTSEL0_ENABLE) + if (counter->state == PERF_COUNTER_STATE_ACTIVE) __pmc_generic_enable(counter, hwc, idx); } @@ -373,6 +470,7 @@ perf_handle_group(struct perf_counter *sibling, u64 *status, u64 *overflown) * Store sibling timestamps (if any): */ list_for_each_entry(counter, &group_leader->sibling_list, list_entry) { + x86_perf_counter_update(counter, &counter->hw, counter->hw.idx); perf_store_irq_data(sibling, counter->hw_event.type); perf_store_irq_data(sibling, atomic64_read(&counter->count)); @@ -403,7 +501,7 @@ static void __smp_perf_counter_interrupt(struct pt_regs *regs, int nmi) again: ack = status; - for_each_bit(bit, (unsigned long *) &status, nr_counters_generic) { + for_each_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) { struct perf_counter *counter = cpuc->counters[bit]; clear_bit(bit, (unsigned long *) &status); @@ -561,6 +659,9 @@ void __init init_hw_perf_counters(void) perf_max_counters = nr_counters_generic; printk(KERN_INFO "... bit width: %d\n", eax.split.bit_width); + counter_value_mask = (1ULL << eax.split.bit_width) - 1; + printk(KERN_INFO "... value mask: %016Lx\n", counter_value_mask); + printk(KERN_INFO "... mask length: %d\n", eax.split.mask_length); nr_counters_fixed = edx.split.num_counters_fixed; -- 2.39.5