Messages in this thread | | | From | Yafang Shao <> | Date | Wed, 6 Mar 2019 18:15:39 +0800 | Subject | Re: [PATCH] sched: fair: fix missed CONFIG_SCHEDSTATS |
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On Wed, Mar 6, 2019 at 6:09 PM Peter Zijlstra <peterz@infradead.org> wrote: > > 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. >
My compiler is GCC-7.3.0. I don't know which comipler could be smart enough to remove the definition of these tracepoints. Could you pls. tell me what compiler you are using ?
> > @@ -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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