sched: Disable NEW_FAIR_SLEEPERS for now

Nikos Chantziaras and Jens Axboe reported that turning off
NEW_FAIR_SLEEPERS improves desktop interactivity visibly.

Nikos described his experiences the following way:

  " With this setting, I can do "nice -n 19 make -j20" and
    still have a very smooth desktop and watch a movie at
    the same time.  Various other annoyances (like the
    "logout/shutdown/restart" dialog of KDE not appearing
    at all until the background fade-out effect has finished)
    are also gone.  So this seems to be the single most
    important setting that vastly improves desktop behavior,
    at least here. "

Jens described it the following way, referring to a 10-seconds
xmodmap scheduling delay he was trying to debug:

  " Then I tried switching NO_NEW_FAIR_SLEEPERS on, and then
    I get:

    Performance counter stats for 'xmodmap .xmodmap-carl':

         9.009137  task-clock-msecs         #      0.447 CPUs
               18  context-switches         #      0.002 M/sec
                1  CPU-migrations           #      0.000 M/sec
              315  page-faults              #      0.035 M/sec

    0.020167093  seconds time elapsed

    Woot! "

So disable it for now. In perf trace output i can see weird
delta timestamps:

  cc1-9943  [001]  2802.059479616: sched_stat_wait: task: as:9944 wait: 2801938766276 [ns]

That nsec field is not supposed to be that large. More digging
is needed - but lets turn it off while the real bug is found.

Reported-by: Nikos Chantziaras <[email protected]>
Tested-by: Nikos Chantziaras <[email protected]>
Reported-by: Jens Axboe <[email protected]>
Tested-by: Jens Axboe <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Mike Galbraith <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions