Messages in this thread | | | Date | Wed, 6 Mar 2019 12:27:07 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH] sched: fair: fix missed CONFIG_SCHEDSTATS |
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On Wed, Mar 06, 2019 at 06:15:39PM +0800, Yafang Shao wrote: > 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 ?
Just look at the generated code...
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