lkml.org 
[lkml]   [2019]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH] sched: fair: fix missed CONFIG_SCHEDSTATS
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
> >

\
 
 \ /
  Last update: 2019-03-06 11:16    [W:0.066 / U:80.656 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site