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 <mingo@elte.hu>
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@ -888,6 +888,54 @@ static const struct hw_perf_counter_ops perf_ops_task_clock = {
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.hw_perf_counter_read = task_clock_perf_counter_read,
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};
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static u64 get_page_faults(void)
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{
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struct task_struct *curr = current;
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return curr->maj_flt + curr->min_flt;
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}
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static void page_faults_perf_counter_update(struct perf_counter *counter)
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{
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u64 prev, now;
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s64 delta;
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prev = atomic64_read(&counter->hw.prev_count);
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now = get_page_faults();
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atomic64_set(&counter->hw.prev_count, now);
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delta = now - prev;
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if (WARN_ON_ONCE(delta < 0))
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delta = 0;
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atomic64_add(delta, &counter->count);
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}
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static void page_faults_perf_counter_read(struct perf_counter *counter)
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{
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page_faults_perf_counter_update(counter);
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}
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static void page_faults_perf_counter_enable(struct perf_counter *counter)
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{
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/*
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* page-faults is a per-task value already,
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* so we dont have to clear it on switch-in.
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*/
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}
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static void page_faults_perf_counter_disable(struct perf_counter *counter)
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{
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page_faults_perf_counter_update(counter);
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}
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static const struct hw_perf_counter_ops perf_ops_page_faults = {
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.hw_perf_counter_enable = page_faults_perf_counter_enable,
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.hw_perf_counter_disable = page_faults_perf_counter_disable,
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.hw_perf_counter_read = page_faults_perf_counter_read,
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};
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static u64 get_context_switches(void)
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{
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struct task_struct *curr = current;
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@ -994,6 +1042,9 @@ sw_perf_counter_init(struct perf_counter *counter)
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case PERF_COUNT_TASK_CLOCK:
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hw_ops = &perf_ops_task_clock;
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break;
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case PERF_COUNT_PAGE_FAULTS:
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hw_ops = &perf_ops_page_faults;
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break;
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case PERF_COUNT_CONTEXT_SWITCHES:
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hw_ops = &perf_ops_context_switches;
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break;
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