Messages in this thread Patch in this message | | | From | Cong Wang <> | Subject | [PATCH] sched: split sched_switch trace event into two | Date | Wed, 24 Jun 2015 16:19:33 -0700 |
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Currently we only have one sched_switch trace event for task switching, which is generated very early during task switch. When we try to monitor per-container events, this is not what we expect.
For example, we have a process A which is in the cgroup we monitor, and process B which isn't, when kernel switches from B to A, the sched_switch event is not recorded for this cgroup since it belongs to B (current process is still B util we finish the switch), but we require this event to signal that process A in this cgroup gets scheduled. This is crucial for calculating schedule latency.
So split the sched_switch event into two: sched_in event before we perform the switch, and sched_out event after we perform the switch.
For compatibility, the sched_switch event is not touched.
Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Cong Wang <cwang@twopensource.com> --- include/trace/events/sched.h | 51 +++++++++++++++++++++++++++++++++++++++++++- kernel/sched/core.c | 2 ++ 2 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index d57a575..c31f1e0 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -112,8 +112,57 @@ static inline long __trace_sched_switch_state(struct task_struct *p) #endif /* CREATE_TRACE_POINTS */ /* - * Tracepoint for task switches, performed by the scheduler: + * Tracepoints for task switches, performed by the scheduler: */ +TRACE_EVENT(sched_out, + + TP_PROTO(struct task_struct *curr), + + TP_ARGS(curr), + + TP_STRUCT__entry( + __array( char, comm, TASK_COMM_LEN ) + __field( int, prio ) + __field( long, state ) + ), + + TP_fast_assign( + __entry->prio = curr->prio; + __entry->state = __trace_sched_switch_state(curr); + memcpy(__entry->comm, curr->comm, TASK_COMM_LEN); + ), + + TP_printk("comm=%s prio=%d state=%s%s", + __entry->comm, __entry->prio, + __entry->state & (TASK_STATE_MAX-1) ? + __print_flags(__entry->state & (TASK_STATE_MAX-1), "|", + { 1, "S"} , { 2, "D" }, { 4, "T" }, { 8, "t" }, + { 16, "Z" }, { 32, "X" }, { 64, "x" }, + { 128, "K" }, { 256, "W" }, { 512, "P" }, + { 1024, "N" }) : "R", + __entry->state & TASK_STATE_MAX ? "+" : "") +); + +TRACE_EVENT(sched_in, + + TP_PROTO(struct task_struct *next), + + TP_ARGS(next), + + TP_STRUCT__entry( + __array( char, comm, TASK_COMM_LEN ) + __field( int, prio ) + ), + + TP_fast_assign( + memcpy(__entry->comm, next->comm, TASK_COMM_LEN); + __entry->prio = next->prio; + ), + + TP_printk("comm=%s prio=%d", + __entry->comm, __entry->prio) +); + TRACE_EVENT(sched_switch, TP_PROTO(struct task_struct *prev, diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c86935a..681fc50 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2219,6 +2219,7 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev, struct task_struct *next) { trace_sched_switch(prev, next); + trace_sched_out(prev); sched_info_switch(rq, prev, next); perf_event_task_sched_out(prev, next); fire_sched_out_preempt_notifiers(prev, next); @@ -2288,6 +2289,7 @@ static struct rq *finish_task_switch(struct task_struct *prev) } tick_nohz_task_switch(current); + trace_sched_in(current); return rq; } -- 1.8.3.1
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