Messages in this thread Patch in this message | | | From | Alexander Shishkin <> | Subject | [PATCH v4 11/22] perf: add ITRACE_START record to indicate that tracing has started | Date | Wed, 20 Aug 2014 15:36:08 +0300 |
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For counters such as instruction tracing, it is useful for the decoder to know which tasks are running when the event is first scheduled in, before the first sched_switch.
To single out such instruction tracing pmus, this patch alse introduces ITRACE PMU capability.
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> --- include/linux/perf_event.h | 4 ++++ include/uapi/linux/perf_event.h | 11 +++++++++++ kernel/events/core.c | 41 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 56 insertions(+)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 63016a0e32..bcfd7a9d84 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -127,6 +127,9 @@ struct hw_perf_event { /* for tp_event->class */ struct list_head tp_list; }; + struct { /* itrace */ + int itrace_started; + }; #ifdef CONFIG_HAVE_HW_BREAKPOINT struct { /* breakpoint */ /* @@ -174,6 +177,7 @@ struct perf_event; #define PERF_PMU_CAP_AUX_NO_SG 0x02 #define PERF_PMU_CAP_AUX_SW_DOUBLEBUF 0x04 #define PERF_PMU_CAP_EXCLUSIVE 0x08 +#define PERF_PMU_CAP_ITRACE 0x10 /** * struct pmu - generic performance monitoring unit diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 507b5e1f5b..349c261f93 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -752,6 +752,17 @@ enum perf_event_type { */ PERF_RECORD_AUX = 11, + /* + * Indicates that instruction trace has started + * + * struct { + * struct perf_event_header header; + * u32 pid; + * u32 tid; + * }; + */ + PERF_RECORD_ITRACE_START = 12, + PERF_RECORD_MAX, /* non-ABI */ }; diff --git a/kernel/events/core.c b/kernel/events/core.c index c4551ac324..b82392911a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1722,6 +1722,7 @@ static void perf_set_shadow_time(struct perf_event *event, #define MAX_INTERRUPTS (~0ULL) static void perf_log_throttle(struct perf_event *event, int enable); +static void perf_log_itrace_start(struct perf_event *event); static int event_sched_in(struct perf_event *event, @@ -1756,6 +1757,8 @@ event_sched_in(struct perf_event *event, perf_pmu_disable(event->pmu); + perf_log_itrace_start(event); + if (event->pmu->add(event, PERF_EF_START)) { event->state = PERF_EVENT_STATE_INACTIVE; event->oncpu = -1; @@ -5623,6 +5626,44 @@ static void perf_log_throttle(struct perf_event *event, int enable) perf_output_end(&handle); } +static void perf_log_itrace_start(struct perf_event *event) +{ + struct perf_output_handle handle; + struct perf_sample_data sample; + struct perf_aux_event { + struct perf_event_header header; + u32 pid; + u32 tid; + } rec; + int ret; + + if (event->parent) + event = event->parent; + + if (!(event->pmu->capabilities & PERF_PMU_CAP_ITRACE) || + event->hw.itrace_started) + return; + + event->hw.itrace_started = 1; + + rec.header.type = PERF_RECORD_ITRACE_START; + rec.header.misc = 0; + rec.header.size = sizeof(rec); + rec.pid = perf_event_pid(event, current); + rec.tid = perf_event_tid(event, current); + + perf_event_header__init_id(&rec.header, &sample, event); + ret = perf_output_begin(&handle, event, rec.header.size); + + if (ret) + return; + + perf_output_put(&handle, rec); + perf_event__output_id_sample(event, &handle, &sample); + + perf_output_end(&handle); +} + /* * Generic event overflow handling, sampling. */ -- 2.1.0
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