perf_events: Add fast-path to the rescheduling code
Implement correct fastpath scheduling, i.e., reuse previous assignment. Signed-off-by: Stephane Eranian <eranian@google.com> [ split from larger patch] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <4b588464.1818d00a.4456.383b@mx.google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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1da53e0230
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8113070d66
1 changed files with 61 additions and 30 deletions
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@ -1244,6 +1244,46 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
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constraints[i]);
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}
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/*
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* fastpath, try to reuse previous register
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*/
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for (i = 0, num = n; i < n; i++, num--) {
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hwc = &cpuc->event_list[i]->hw;
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c = (unsigned long *)constraints[i];
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/* never assigned */
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if (hwc->idx == -1)
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break;
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/* constraint still honored */
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if (!test_bit(hwc->idx, c))
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break;
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/* not already used */
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if (test_bit(hwc->idx, used_mask))
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break;
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#if 0
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pr_debug("CPU%d fast config=0x%llx idx=%d assign=%c\n",
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smp_processor_id(),
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hwc->config,
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hwc->idx,
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assign ? 'y' : 'n');
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#endif
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set_bit(hwc->idx, used_mask);
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if (assign)
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assign[i] = hwc->idx;
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}
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if (!num)
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goto done;
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/*
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* begin slow path
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*/
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bitmap_zero(used_mask, X86_PMC_IDX_MAX);
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/*
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* weight = number of possible counters
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*
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@ -1263,10 +1303,9 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
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if (x86_pmu.num_events_fixed)
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wmax++;
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num = n;
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for (w = 1; num && w <= wmax; w++) {
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for (w = 1, num = n; num && w <= wmax; w++) {
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/* for each event */
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for (i = 0; i < n; i++) {
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for (i = 0; num && i < n; i++) {
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c = (unsigned long *)constraints[i];
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hwc = &cpuc->event_list[i]->hw;
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@ -1274,28 +1313,6 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
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if (weight != w)
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continue;
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/*
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* try to reuse previous assignment
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*
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* This is possible despite the fact that
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* events or events order may have changed.
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*
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* What matters is the level of constraints
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* of an event and this is constant for now.
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*
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* This is possible also because we always
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* scan from most to least constrained. Thus,
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* if a counter can be reused, it means no,
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* more constrained events, needed it. And
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* next events will either compete for it
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* (which cannot be solved anyway) or they
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* have fewer constraints, and they can use
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* another counter.
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*/
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j = hwc->idx;
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if (j != -1 && !test_bit(j, used_mask))
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goto skip;
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for_each_bit(j, c, X86_PMC_IDX_MAX) {
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if (!test_bit(j, used_mask))
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break;
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@ -1303,22 +1320,23 @@ static int x86_schedule_events(struct cpu_hw_events *cpuc, int n, int *assign)
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if (j == X86_PMC_IDX_MAX)
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break;
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skip:
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set_bit(j, used_mask);
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#if 0
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pr_debug("CPU%d config=0x%llx idx=%d assign=%c\n",
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pr_debug("CPU%d slow config=0x%llx idx=%d assign=%c\n",
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smp_processor_id(),
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hwc->config,
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j,
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assign ? 'y' : 'n');
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#endif
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set_bit(j, used_mask);
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if (assign)
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assign[i] = j;
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num--;
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}
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}
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done:
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/*
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* scheduling failed or is just a simulation,
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* free resources if necessary
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@ -1357,7 +1375,7 @@ static int collect_events(struct cpu_hw_events *cpuc, struct perf_event *leader,
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list_for_each_entry(event, &leader->sibling_list, group_entry) {
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if (!is_x86_event(event) ||
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event->state == PERF_EVENT_STATE_OFF)
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event->state <= PERF_EVENT_STATE_OFF)
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continue;
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if (n >= max_count)
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@ -2184,6 +2202,8 @@ static void amd_get_event_constraints(struct cpu_hw_events *cpuc,
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struct perf_event *event,
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u64 *idxmsk)
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{
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/* no constraints, means supports all generic counters */
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bitmap_fill((unsigned long *)idxmsk, x86_pmu.num_events);
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}
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static int x86_event_sched_in(struct perf_event *event,
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@ -2258,7 +2278,7 @@ int hw_perf_group_sched_in(struct perf_event *leader,
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n1 = 1;
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list_for_each_entry(sub, &leader->sibling_list, group_entry) {
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if (sub->state != PERF_EVENT_STATE_OFF) {
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if (sub->state > PERF_EVENT_STATE_OFF) {
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ret = x86_event_sched_in(sub, cpuctx, cpu);
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if (ret)
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goto undo;
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@ -2613,12 +2633,23 @@ static int validate_group(struct perf_event *event)
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const struct pmu *hw_perf_event_init(struct perf_event *event)
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{
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const struct pmu *tmp;
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int err;
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err = __hw_perf_event_init(event);
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if (!err) {
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/*
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* we temporarily connect event to its pmu
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* such that validate_group() can classify
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* it as an x86 event using is_x86_event()
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*/
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tmp = event->pmu;
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event->pmu = &pmu;
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if (event->group_leader != event)
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err = validate_group(event);
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event->pmu = tmp;
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}
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if (err) {
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if (event->destroy)
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