Messages in this thread | | | Date | Wed, 6 Mar 2019 11:09:07 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: fair: fix missed CONFIG_SCHEDSTATS |
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On Wed, Mar 06, 2019 at 04:43:46PM +0800, Yafang Shao wrote: > 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.
Yeah, lets not sprinkle #ifdef. Big fat NAK.
Also, the below seem to indicate your compiler is stupid. Without CONFIG_SCHEDSTAT, schedstat_enabled() should be a constant 0 and DCE should delete all code.
> @@ -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 >
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