When I'm using trace_sched_stat_{iowait, blocked, wait, sleep} to
measure how long the processes are stalled, there's always no output from
trace_pipe while there're really some tasks in uninterruptible sleep
state. That makes me confused, so I try to investigate why.
Finally I find the reason is that CONFIG_SCHEDSTATS is not set.To avoid such kind of confusion, we should not expose these tracepoints if CONFIG_SCHEDSTATS is not set. Signed-off-by: Yafang Shao <[email protected]> --- include/trace/events/sched.h | 3 ++- kernel/sched/fair.c | 13 ++++++++++++- 2 files changed, 14 insertions(+), 2 deletions(-) diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index 9a4bdfa..a261da8 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -336,6 +336,7 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct * __entry->pid, __entry->old_pid) ); +#ifdef CONFIG_SCHEDSTATS /* * XXX the below sched_stat tracepoints only apply to SCHED_OTHER/BATCH/IDLE * adding sched_stat support to SCHED_FIFO/RR would be welcome. @@ -363,7 +364,6 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct * (unsigned long long)__entry->delay) ); - /* * Tracepoint for accounting wait time (time the task is runnable * but not actually running due to scheduler contention). @@ -394,6 +394,7 @@ static inline long __trace_sched_switch_state(bool preempt, struct task_struct * DEFINE_EVENT(sched_stat_template, sched_stat_blocked, TP_PROTO(struct task_struct *tsk, u64 delay), TP_ARGS(tsk, delay)); +#endif /* * Tracepoint for accounting runtime (time the task is executing diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8213ff6..a8006c9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -855,6 +855,7 @@ static void update_curr_fair(struct rq *rq) static inline void update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) { +#ifdef CONFIG_SCHEDSTATS u64 wait_start, prev_wait_start; if (!schedstat_enabled()) @@ -868,11 +869,13 @@ static void update_curr_fair(struct rq *rq) wait_start -= prev_wait_start; __schedstat_set(se->statistics.wait_start, wait_start); +#endif } static inline void update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) { +#ifdef CONFIG_SCHEDSTATS struct task_struct *p; u64 delta; @@ -900,11 +903,13 @@ static void update_curr_fair(struct rq *rq) __schedstat_inc(se->statistics.wait_count); __schedstat_add(se->statistics.wait_sum, delta); __schedstat_set(se->statistics.wait_start, 0); +#endif } static inline void update_stats_enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) { +#ifdef CONFIG_SCHEDSTATS struct task_struct *tsk = NULL; u64 sleep_start, block_start; @@ -968,6 +973,7 @@ static void update_curr_fair(struct rq *rq) account_scheduler_latency(tsk, delta >> 10, 0); } } +#endif } /* @@ -976,6 +982,7 @@ static void update_curr_fair(struct rq *rq) static inline void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { +#ifdef CONFIG_SCHEDSTATS if (!schedstat_enabled()) return; @@ -988,12 +995,13 @@ static void update_curr_fair(struct rq *rq) if (flags & ENQUEUE_WAKEUP) update_stats_enqueue_sleeper(cfs_rq, se); +#endif } static inline void update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { - +#ifdef CONFIG_SCHEDSTATS if (!schedstat_enabled()) return; @@ -1014,6 +1022,7 @@ static void update_curr_fair(struct rq *rq) __schedstat_set(se->statistics.block_start, rq_clock(rq_of(cfs_rq))); } +#endif } /* @@ -4090,6 +4099,7 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) update_stats_curr_start(cfs_rq, se); cfs_rq->curr = se; +#ifdef CONFIG_SCHEDSTATS /* * Track our maximum slice length, if the CPU's load is at * least twice that of our own weight (i.e. dont track it @@ -4100,6 +4110,7 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) max((u64)schedstat_val(se->statistics.slice_max), se->sum_exec_runtime - se->prev_sum_exec_runtime)); } +#endif se->prev_sum_exec_runtime = se->sum_exec_runtime; } -- 1.8.3.1
