Re: CFS review

[Ingo Molnar]

* Al Boldi <a1426z@xxxxxxxxx> wrote:

> I have narrowed it down a bit to add_wait_runtime.

the scheduler is a red herring here. Could you "strace -ttt -TTT" one of 
the glxgears instances (and send us the cfs-debug-info.sh output, with 
CONFIG_SCHED_DEBUG=y and CONFIG_SCHEDSTATS=y as requested before) so 
that we can have a closer look?

i reproduced something similar and there the stall is caused by 1+ 
second select() delays on the X client<->server socket. The scheduler 
stats agree with that:

 se.sleep_max             :          2194711437
 se.block_max             :                   0
 se.exec_max              :              977446
 se.wait_max              :             1912321

the scheduler itself had a worst-case scheduling delay of 1.9 
milliseconds for that glxgears instance (which is perfectly good - in 
fact - excellent interactivity) - but the task had a maximum sleep time 
of 2.19 seconds. So the 'glitch' was not caused by the scheduler.

	Ingo
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