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author | Jupyung Lee | 2009-11-17 18:51:40 +0900 |
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committer | Ingo Molnar | 2009-12-09 10:03:06 +0100 |
commit | a65ac745e47e91f9d98dbf07f22ed0492e34d998 (patch) | |
tree | 246b0953cbf4e2d890d71d01cbfb070f8e4b1811 /Documentation/logo.txt | |
parent | cd29fe6f2637cc2ccbda5ac65f5332d6bf5fa3c6 (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/logo.txt')
0 files changed, 0 insertions, 0 deletions