perf/x86: Add a few more comments (c347a2f1) · Commits · 戴 / test

arch/x86/kernel/cpu/perf_event.c

+33 −14

Original line number	Diff line number	Diff line
		@@ -892,7 +892,6 @@ static void x86_pmu_enable(struct pmu *pmu)
		* hw_perf_group_sched_in() or x86_pmu_enable()
		*
		* step1: save events moving to new counters
		* step2: reprogram moved events into new counters
		*/
		for (i = 0; i < n_running; i++) {
		event = cpuc->event_list[i];
		@@ -918,6 +917,9 @@ static void x86_pmu_enable(struct pmu *pmu)
		x86_pmu_stop(event, PERF_EF_UPDATE);
		}

		/*
		* step2: reprogram moved events into new counters
		*/
		for (i = 0; i < cpuc->n_events; i++) {
		event = cpuc->event_list[i];
		hwc = &event->hw;
		@@ -1043,7 +1045,7 @@ static int x86_pmu_add(struct perf_event *event, int flags)
		/*
		* If group events scheduling transaction was started,
		* skip the schedulability test here, it will be performed
		* at commit time (->commit_txn) as a whole
		* at commit time (->commit_txn) as a whole.
		*/
		if (cpuc->group_flag & PERF_EVENT_TXN)
		goto done_collect;
		@@ -1058,6 +1060,10 @@ static int x86_pmu_add(struct perf_event *event, int flags)
		memcpy(cpuc->assign, assign, n*sizeof(int));

		done_collect:
		/*
		* Commit the collect_events() state. See x86_pmu_del() and
		* x86_pmu_*_txn().
		*/
		cpuc->n_events = n;
		cpuc->n_added += n - n0;
		cpuc->n_txn += n - n0;
		@@ -1183,28 +1189,38 @@ static void x86_pmu_del(struct perf_event *event, int flags)
		* If we're called during a txn, we don't need to do anything.
		* The events never got scheduled and ->cancel_txn will truncate
		* the event_list.
		*
		* XXX assumes any ->del() called during a TXN will only be on
		* an event added during that same TXN.
		*/
		if (cpuc->group_flag & PERF_EVENT_TXN)
		return;

		/*
		* Not a TXN, therefore cleanup properly.
		*/
		x86_pmu_stop(event, PERF_EF_UPDATE);

		for (i = 0; i < cpuc->n_events; i++) {
		if (event == cpuc->event_list[i]) {
		if (event == cpuc->event_list[i])
		break;
		}

		if (WARN_ON_ONCE(i == cpuc->n_events)) /* called ->del() without ->add() ? */
		return;

		/* If we have a newly added event; make sure to decrease n_added. */
		if (i >= cpuc->n_events - cpuc->n_added)
		--cpuc->n_added;

		if (x86_pmu.put_event_constraints)
		x86_pmu.put_event_constraints(cpuc, event);

		/* Delete the array entry. */
		while (++i < cpuc->n_events)
		cpuc->event_list[i-1] = cpuc->event_list[i];

		--cpuc->n_events;
		break;
		}
		}

		perf_event_update_userpage(event);
		}

		@@ -1598,7 +1614,8 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
		{
		__this_cpu_and(cpu_hw_events.group_flag, ~PERF_EVENT_TXN);
		/*
		* Truncate the collected events.
		* Truncate collected array by the number of events added in this
		* transaction. See x86_pmu_add() and x86_pmu_*_txn().
		*/
		__this_cpu_sub(cpu_hw_events.n_added, __this_cpu_read(cpu_hw_events.n_txn));
		__this_cpu_sub(cpu_hw_events.n_events, __this_cpu_read(cpu_hw_events.n_txn));
		@@ -1609,6 +1626,8 @@ static void x86_pmu_cancel_txn(struct pmu *pmu)
		* Commit group events scheduling transaction
		* Perform the group schedulability test as a whole
		* Return 0 if success
		*
		* Does not cancel the transaction on failure; expects the caller to do this.
		*/
		static int x86_pmu_commit_txn(struct pmu *pmu)
		{

arch/x86/kernel/cpu/perf_event.h

+5 −3

Original line number	Diff line number	Diff line
		@@ -130,9 +130,11 @@ struct cpu_hw_events {
		unsigned long running[BITS_TO_LONGS(X86_PMC_IDX_MAX)];
		int enabled;

		int n_events;
		int n_added;
		int n_txn;
		int n_events; /* the # of events in the below arrays */
		int n_added; /* the # last events in the below arrays;
		they've never been enabled yet */
		int n_txn; /* the # last events in the below arrays;
		added in the current transaction */
		int assign[X86_PMC_IDX_MAX]; /* event to counter assignment */
		u64 tags[X86_PMC_IDX_MAX];
		struct perf_event event_list[X86_PMC_IDX_MAX]; / in enabled order */

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