From 721a669b7225edeeb0ca8e2bf71b83882326a71b Mon Sep 17 00:00:00 2001 From: Soeren Sandmann Date: Tue, 15 Sep 2009 14:33:08 +0200 Subject: perf events: Fix swevent hrtimer sampling by keeping track of remaining time when enabling/disabling swevent hrtimers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Make the hrtimer based events work for sysprof. Whenever a swevent is scheduled out, the hrtimer is canceled. When it is scheduled back in, the timer is restarted. This happens every scheduler tick, which means the timer never expired because it was getting repeatedly restarted over and over with the same period. To fix that, save the remaining time when disabling; when reenabling, use that saved time as the period instead of the user-specified sampling period. Also, move the starting and stopping of the hrtimers to helper functions instead of duplicating the code. Signed-off-by: Søren Sandmann Pedersen LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 61 +++++++++++++++++++++++++++++++++++------------------ 1 file changed, 41 insertions(+), 20 deletions(-) (limited to 'kernel') diff --git a/kernel/perf_event.c b/kernel/perf_event.c index afb7ef3dbc4..33ff019f9aa 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3969,6 +3969,42 @@ static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer) return ret; } +static void perf_swevent_start_hrtimer(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + + hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); + hwc->hrtimer.function = perf_swevent_hrtimer; + if (hwc->sample_period) { + u64 period; + + if (hwc->remaining) { + if (hwc->remaining < 0) + period = 10000; + else + period = hwc->remaining; + hwc->remaining = 0; + } else { + period = max_t(u64, 10000, hwc->sample_period); + } + __hrtimer_start_range_ns(&hwc->hrtimer, + ns_to_ktime(period), 0, + HRTIMER_MODE_REL, 0); + } +} + +static void perf_swevent_cancel_hrtimer(struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + + if (hwc->sample_period) { + ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer); + hwc->remaining = ktime_to_ns(remaining); + + hrtimer_cancel(&hwc->hrtimer); + } +} + /* * Software event: cpu wall time clock */ @@ -3991,22 +4027,14 @@ static int cpu_clock_perf_event_enable(struct perf_event *event) int cpu = raw_smp_processor_id(); atomic64_set(&hwc->prev_count, cpu_clock(cpu)); - hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - hwc->hrtimer.function = perf_swevent_hrtimer; - if (hwc->sample_period) { - u64 period = max_t(u64, 10000, hwc->sample_period); - __hrtimer_start_range_ns(&hwc->hrtimer, - ns_to_ktime(period), 0, - HRTIMER_MODE_REL, 0); - } + perf_swevent_start_hrtimer(event); return 0; } static void cpu_clock_perf_event_disable(struct perf_event *event) { - if (event->hw.sample_period) - hrtimer_cancel(&event->hw.hrtimer); + perf_swevent_cancel_hrtimer(event); cpu_clock_perf_event_update(event); } @@ -4043,22 +4071,15 @@ static int task_clock_perf_event_enable(struct perf_event *event) now = event->ctx->time; atomic64_set(&hwc->prev_count, now); - hrtimer_init(&hwc->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); - hwc->hrtimer.function = perf_swevent_hrtimer; - if (hwc->sample_period) { - u64 period = max_t(u64, 10000, hwc->sample_period); - __hrtimer_start_range_ns(&hwc->hrtimer, - ns_to_ktime(period), 0, - HRTIMER_MODE_REL, 0); - } + + perf_swevent_start_hrtimer(event); return 0; } static void task_clock_perf_event_disable(struct perf_event *event) { - if (event->hw.sample_period) - hrtimer_cancel(&event->hw.hrtimer); + perf_swevent_cancel_hrtimer(event); task_clock_perf_event_update(event, event->ctx->time); } -- cgit v1.2.3-18-g5258 From 54f4407608c59712a8f5ec1e10dfac40bef5a2e7 Mon Sep 17 00:00:00 2001 From: Soeren Sandmann Date: Thu, 22 Oct 2009 18:34:08 +0200 Subject: perf events: Don't generate events for the idle task when exclude_idle is set MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Getting samples for the idle task is often not interesting, so don't generate them when exclude_idle is set for the event in question. Signed-off-by: Søren Sandmann Pedersen Cc: Peter Zijlstra Cc: Mike Galbraith Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Cc: Frederic Weisbecker Cc: Steven Rostedt LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_event.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'kernel') diff --git a/kernel/perf_event.c b/kernel/perf_event.c index 33ff019f9aa..7f29643c898 100644 --- a/kernel/perf_event.c +++ b/kernel/perf_event.c @@ -3959,8 +3959,9 @@ static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer) regs = task_pt_regs(current); if (regs) { - if (perf_event_overflow(event, 0, &data, regs)) - ret = HRTIMER_NORESTART; + if (!(event->attr.exclude_idle && current->pid == 0)) + if (perf_event_overflow(event, 0, &data, regs)) + ret = HRTIMER_NORESTART; } period = max_t(u64, 10000, event->hw.sample_period); -- cgit v1.2.3-18-g5258