diff options
| -rw-r--r-- | include/uapi/linux/perf_event.h | 31 | ||||
| -rw-r--r-- | kernel/events/core.c | 103 |
2 files changed, 133 insertions, 1 deletions
diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index d97f84c080da..022d0acf7df0 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -330,7 +330,8 @@ struct perf_event_attr { mmap2 : 1, /* include mmap with inode data */ comm_exec : 1, /* flag comm events that are due to an exec */ use_clockid : 1, /* use @clockid for time fields */ - __reserved_1 : 38; + context_switch : 1, /* context switch data */ + __reserved_1 : 37; union { __u32 wakeup_events; /* wakeup every n events */ @@ -572,9 +573,11 @@ struct perf_event_mmap_page { /* * PERF_RECORD_MISC_MMAP_DATA and PERF_RECORD_MISC_COMM_EXEC are used on * different events so can reuse the same bit position. + * Ditto PERF_RECORD_MISC_SWITCH_OUT. */ #define PERF_RECORD_MISC_MMAP_DATA (1 << 13) #define PERF_RECORD_MISC_COMM_EXEC (1 << 13) +#define PERF_RECORD_MISC_SWITCH_OUT (1 << 13) /* * Indicates that the content of PERF_SAMPLE_IP points to * the actual instruction that triggered the event. See also @@ -818,6 +821,32 @@ enum perf_event_type { */ PERF_RECORD_LOST_SAMPLES = 13, + /* + * Records a context switch in or out (flagged by + * PERF_RECORD_MISC_SWITCH_OUT). See also + * PERF_RECORD_SWITCH_CPU_WIDE. + * + * struct { + * struct perf_event_header header; + * struct sample_id sample_id; + * }; + */ + PERF_RECORD_SWITCH = 14, + + /* + * CPU-wide version of PERF_RECORD_SWITCH with next_prev_pid and + * next_prev_tid that are the next (switching out) or previous + * (switching in) pid/tid. + * + * struct { + * struct perf_event_header header; + * u32 next_prev_pid; + * u32 next_prev_tid; + * struct sample_id sample_id; + * }; + */ + PERF_RECORD_SWITCH_CPU_WIDE = 15, + PERF_RECORD_MAX, /* non-ABI */ }; diff --git a/kernel/events/core.c b/kernel/events/core.c index d3dae3419b99..ce21143c0d9e 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -163,6 +163,7 @@ static atomic_t nr_mmap_events __read_mostly; static atomic_t nr_comm_events __read_mostly; static atomic_t nr_task_events __read_mostly; static atomic_t nr_freq_events __read_mostly; +static atomic_t nr_switch_events __read_mostly; static LIST_HEAD(pmus); static DEFINE_MUTEX(pmus_lock); @@ -2619,6 +2620,9 @@ static void perf_pmu_sched_task(struct task_struct *prev, local_irq_restore(flags); } +static void perf_event_switch(struct task_struct *task, + struct task_struct *next_prev, bool sched_in); + #define for_each_task_context_nr(ctxn) \ for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++) @@ -2641,6 +2645,9 @@ void __perf_event_task_sched_out(struct task_struct *task, if (__this_cpu_read(perf_sched_cb_usages)) perf_pmu_sched_task(task, next, false); + if (atomic_read(&nr_switch_events)) + perf_event_switch(task, next, false); + for_each_task_context_nr(ctxn) perf_event_context_sched_out(task, ctxn, next); @@ -2831,6 +2838,9 @@ void __perf_event_task_sched_in(struct task_struct *prev, if (atomic_read(this_cpu_ptr(&perf_cgroup_events))) perf_cgroup_sched_in(prev, task); + if (atomic_read(&nr_switch_events)) + perf_event_switch(task, prev, true); + if (__this_cpu_read(perf_sched_cb_usages)) perf_pmu_sched_task(prev, task, true); } @@ -3454,6 +3464,10 @@ static void unaccount_event(struct perf_event *event) atomic_dec(&nr_task_events); if (event->attr.freq) atomic_dec(&nr_freq_events); + if (event->attr.context_switch) { + static_key_slow_dec_deferred(&perf_sched_events); + atomic_dec(&nr_switch_events); + } if (is_cgroup_event(event)) static_key_slow_dec_deferred(&perf_sched_events); if (has_branch_stack(event)) @@ -5982,6 +5996,91 @@ void perf_log_lost_samples(struct perf_event *event, u64 lost) } /* + * context_switch tracking + */ + +struct perf_switch_event { + struct task_struct *task; + struct task_struct *next_prev; + + struct { + struct perf_event_header header; + u32 next_prev_pid; + u32 next_prev_tid; + } event_id; +}; + +static int perf_event_switch_match(struct perf_event *event) +{ + return event->attr.context_switch; +} + +static void perf_event_switch_output(struct perf_event *event, void *data) +{ + struct perf_switch_event *se = data; + struct perf_output_handle handle; + struct perf_sample_data sample; + int ret; + + if (!perf_event_switch_match(event)) + return; + + /* Only CPU-wide events are allowed to see next/prev pid/tid */ + if (event->ctx->task) { + se->event_id.header.type = PERF_RECORD_SWITCH; + se->event_id.header.size = sizeof(se->event_id.header); + } else { + se->event_id.header.type = PERF_RECORD_SWITCH_CPU_WIDE; + se->event_id.header.size = sizeof(se->event_id); + se->event_id.next_prev_pid = + perf_event_pid(event, se->next_prev); + se->event_id.next_prev_tid = + perf_event_tid(event, se->next_prev); + } + + perf_event_header__init_id(&se->event_id.header, &sample, event); + + ret = perf_output_begin(&handle, event, se->event_id.header.size); + if (ret) + return; + + if (event->ctx->task) + perf_output_put(&handle, se->event_id.header); + else + perf_output_put(&handle, se->event_id); + + perf_event__output_id_sample(event, &handle, &sample); + + perf_output_end(&handle); +} + +static void perf_event_switch(struct task_struct *task, + struct task_struct *next_prev, bool sched_in) +{ + struct perf_switch_event switch_event; + + /* N.B. caller checks nr_switch_events != 0 */ + + switch_event = (struct perf_switch_event){ + .task = task, + .next_prev = next_prev, + .event_id = { + .header = { + /* .type */ + .misc = sched_in ? 0 : PERF_RECORD_MISC_SWITCH_OUT, + /* .size */ + }, + /* .next_prev_pid */ + /* .next_prev_tid */ + }, + }; + + perf_event_aux(perf_event_switch_output, + &switch_event, + NULL); +} + +/* * IRQ throttle logging */ @@ -7479,6 +7578,10 @@ static void account_event(struct perf_event *event) if (atomic_inc_return(&nr_freq_events) == 1) tick_nohz_full_kick_all(); } + if (event->attr.context_switch) { + atomic_inc(&nr_switch_events); + static_key_slow_inc(&perf_sched_events.key); + } if (has_branch_stack(event)) static_key_slow_inc(&perf_sched_events.key); if (is_cgroup_event(event)) |