aboutsummaryrefslogtreecommitdiff
path: root/Documentation/futex-requeue-pi.txt
diff options
context:
space:
mode:
authorJupyung Lee2009-11-17 18:51:40 +0900
committerIngo Molnar2009-12-09 10:03:06 +0100
commita65ac745e47e91f9d98dbf07f22ed0492e34d998 (patch)
tree246b0953cbf4e2d890d71d01cbfb070f8e4b1811 /Documentation/futex-requeue-pi.txt
parentcd29fe6f2637cc2ccbda5ac65f5332d6bf5fa3c6 (diff)
sched: Move update_curr() in check_preempt_wakeup() to avoid redundant call
If a RT task is woken up while a non-RT task is running, check_preempt_wakeup() is called to check whether the new task can preempt the old task. The function returns quickly without going deeper because it is apparent that a RT task can always preempt a non-RT task. In this situation, check_preempt_wakeup() always calls update_curr() to update vruntime value of the currently running task. However, the function call is unnecessary and redundant at that moment because (1) a non-RT task can always be preempted by a RT task regardless of its vruntime value, and (2) update_curr() will be called shortly when the context switch between two occurs. By moving update_curr() in check_preempt_wakeup(), we can avoid redundant call to update_curr(), slightly reducing the time taken to wake up RT tasks. Signed-off-by: Jupyung Lee <jupyung@gmail.com> [ Place update_curr() right before the wake_preempt_entity() call, which is the only thing that relies on the updated vruntime ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <1258451500-6714-1-git-send-email-jupyung@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'Documentation/futex-requeue-pi.txt')
0 files changed, 0 insertions, 0 deletions