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author | Ingo Molnar <mingo@elte.hu> | 2008-12-11 13:21:10 +0100 |
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committer | Ingo Molnar <mingo@elte.hu> | 2008-12-11 15:45:52 +0100 |
commit | 5c92d12411dfe5f0f3d1b1c1e2f756245e6f7249 (patch) | |
tree | 498b78f995d917aa513cf15ada480327224c0277 /kernel/perf_counter.c | |
parent | 621a01eac89b5e2f81a4cf576568b31f40a02724 (diff) | |
download | lwn-5c92d12411dfe5f0f3d1b1c1e2f756245e6f7249.tar.gz lwn-5c92d12411dfe5f0f3d1b1c1e2f756245e6f7249.zip |
perf counters: implement PERF_COUNT_CPU_CLOCK
Impact: add new perf-counter type
The 'CPU clock' counter counts the amount of CPU clock time that is
elapsing, in nanoseconds. (regardless of how much of it the task is
spending on a CPU executing)
This counter type is a Linux kernel based abstraction, it is available
even if the hardware does not support native hardware performance counters.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/perf_counter.c')
-rw-r--r-- | kernel/perf_counter.c | 95 |
1 files changed, 82 insertions, 13 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index e6e41ca95463..506286e5ba63 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -37,15 +37,15 @@ static DEFINE_MUTEX(perf_resource_mutex); /* * Architecture provided APIs - weak aliases: */ -extern __weak struct hw_perf_counter_ops * +extern __weak const struct hw_perf_counter_ops * hw_perf_counter_init(struct perf_counter *counter) { return ERR_PTR(-EINVAL); } -void __weak hw_perf_disable_all(void) { } -void __weak hw_perf_enable_all(void) { } -void __weak hw_perf_counter_setup(void) { } +u64 __weak hw_perf_disable_all(void) { return 0; } +void __weak hw_perf_restore_ctrl(u64 ctrl) { } +void __weak hw_perf_counter_setup(void) { } #if BITS_PER_LONG == 64 @@ -58,6 +58,16 @@ static inline u64 perf_counter_read_safe(struct perf_counter *counter) return (u64) atomic64_read(&counter->count); } +void atomic64_counter_set(struct perf_counter *counter, u64 val) +{ + atomic64_set(&counter->count, val); +} + +u64 atomic64_counter_read(struct perf_counter *counter) +{ + return atomic64_read(&counter->count); +} + #else /* @@ -79,6 +89,20 @@ static u64 perf_counter_read_safe(struct perf_counter *counter) return cntl | ((u64) cnth) << 32; } +void atomic64_counter_set(struct perf_counter *counter, u64 val64) +{ + u32 *val32 = (void *)&val64; + + atomic_set(counter->count32 + 0, *(val32 + 0)); + atomic_set(counter->count32 + 1, *(val32 + 1)); +} + +u64 atomic64_counter_read(struct perf_counter *counter) +{ + return atomic_read(counter->count32 + 0) | + (u64) atomic_read(counter->count32 + 1) << 32; +} + #endif static void @@ -131,6 +155,7 @@ static void __perf_counter_remove_from_context(void *info) struct perf_cpu_context *cpuctx = &__get_cpu_var(perf_cpu_context); struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; + u64 perf_flags; /* * If this is a task context, we need to check whether it is @@ -155,9 +180,9 @@ 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. */ - hw_perf_disable_all(); + perf_flags = hw_perf_disable_all(); list_del_counter(counter, ctx); - hw_perf_enable_all(); + hw_perf_restore_ctrl(perf_flags); if (!ctx->task) { /* @@ -232,6 +257,7 @@ static void __perf_install_in_context(void *info) struct perf_counter *counter = info; struct perf_counter_context *ctx = counter->ctx; int cpu = smp_processor_id(); + u64 perf_flags; /* * If this is a task context, we need to check whether it is @@ -247,9 +273,9 @@ 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. */ - hw_perf_disable_all(); + perf_flags = hw_perf_disable_all(); list_add_counter(counter, ctx); - hw_perf_enable_all(); + hw_perf_restore_ctrl(perf_flags); ctx->nr_counters++; @@ -457,6 +483,7 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu) { struct perf_counter_context *ctx = &curr->perf_counter_ctx; struct perf_counter *counter; + u64 perf_flags; if (likely(!ctx->nr_counters)) return; @@ -468,13 +495,13 @@ void perf_counter_task_tick(struct task_struct *curr, int cpu) /* * Rotate the first entry last (works just fine for group counters too): */ - hw_perf_disable_all(); + perf_flags = hw_perf_disable_all(); list_for_each_entry(counter, &ctx->counter_list, list_entry) { list_del(&counter->list_entry); list_add_tail(&counter->list_entry, &ctx->counter_list); break; } - hw_perf_enable_all(); + hw_perf_restore_ctrl(perf_flags); spin_unlock(&ctx->lock); @@ -807,6 +834,42 @@ static const struct file_operations perf_fops = { .poll = perf_poll, }; +static void cpu_clock_perf_counter_enable(struct perf_counter *counter) +{ +} + +static void cpu_clock_perf_counter_disable(struct perf_counter *counter) +{ +} + +static void cpu_clock_perf_counter_read(struct perf_counter *counter) +{ + int cpu = raw_smp_processor_id(); + + atomic64_counter_set(counter, cpu_clock(cpu)); +} + +static const struct hw_perf_counter_ops perf_ops_cpu_clock = { + .hw_perf_counter_enable = cpu_clock_perf_counter_enable, + .hw_perf_counter_disable = cpu_clock_perf_counter_disable, + .hw_perf_counter_read = cpu_clock_perf_counter_read, +}; + +static const struct hw_perf_counter_ops * +sw_perf_counter_init(struct perf_counter *counter) +{ + const struct hw_perf_counter_ops *hw_ops = NULL; + + switch (counter->hw_event.type) { + case PERF_COUNT_CPU_CLOCK: + hw_ops = &perf_ops_cpu_clock; + break; + default: + break; + } + return hw_ops; +} + /* * Allocate and initialize a counter structure */ @@ -815,7 +878,7 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, int cpu, struct perf_counter *group_leader) { - struct hw_perf_counter_ops *hw_ops; + const struct hw_perf_counter_ops *hw_ops; struct perf_counter *counter; counter = kzalloc(sizeof(*counter), GFP_KERNEL); @@ -842,7 +905,13 @@ perf_counter_alloc(struct perf_counter_hw_event *hw_event, counter->group_leader = group_leader; counter->hw_ops = NULL; - hw_ops = hw_perf_counter_init(counter); + hw_ops = NULL; + if (!hw_event->raw && hw_event->type < 0) + hw_ops = sw_perf_counter_init(counter); + if (!hw_ops) { + hw_ops = hw_perf_counter_init(counter); + } + if (!hw_ops) { kfree(counter); return NULL; @@ -912,7 +981,7 @@ asmlinkage int sys_perf_counter_open( goto err_put_context; } - ret = -ENOMEM; + ret = -EINVAL; counter = perf_counter_alloc(&hw_event, cpu, group_leader); if (!counter) goto err_put_context; |