From e06c61a879910869aa5bf3f8f634abfee1a7bebc Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 14 Dec 2008 14:44:31 +0100 Subject: [PATCH] perfcounters: add nr-of-faults counter Impact: add new feature, new sw counter Add a counter that counts the number of pagefaults a task is experiencing. Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 51 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index fb11e351e44e..59c52f9ee431 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -888,6 +888,54 @@ static const struct hw_perf_counter_ops perf_ops_task_clock = { .hw_perf_counter_read = task_clock_perf_counter_read, }; +static u64 get_page_faults(void) +{ + struct task_struct *curr = current; + + return curr->maj_flt + curr->min_flt; +} + +static void page_faults_perf_counter_update(struct perf_counter *counter) +{ + u64 prev, now; + s64 delta; + + prev = atomic64_read(&counter->hw.prev_count); + now = get_page_faults(); + + atomic64_set(&counter->hw.prev_count, now); + + delta = now - prev; + if (WARN_ON_ONCE(delta < 0)) + delta = 0; + + atomic64_add(delta, &counter->count); +} + +static void page_faults_perf_counter_read(struct perf_counter *counter) +{ + page_faults_perf_counter_update(counter); +} + +static void page_faults_perf_counter_enable(struct perf_counter *counter) +{ + /* + * page-faults is a per-task value already, + * so we dont have to clear it on switch-in. + */ +} + +static void page_faults_perf_counter_disable(struct perf_counter *counter) +{ + page_faults_perf_counter_update(counter); +} + +static const struct hw_perf_counter_ops perf_ops_page_faults = { + .hw_perf_counter_enable = page_faults_perf_counter_enable, + .hw_perf_counter_disable = page_faults_perf_counter_disable, + .hw_perf_counter_read = page_faults_perf_counter_read, +}; + static u64 get_context_switches(void) { struct task_struct *curr = current; @@ -994,6 +1042,9 @@ sw_perf_counter_init(struct perf_counter *counter) case PERF_COUNT_TASK_CLOCK: hw_ops = &perf_ops_task_clock; break; + case PERF_COUNT_PAGE_FAULTS: + hw_ops = &perf_ops_page_faults; + break; case PERF_COUNT_CONTEXT_SWITCHES: hw_ops = &perf_ops_context_switches; break; -- 2.20.1