Messages in this thread Patch in this message | | | Subject | Re: [patch 10/12] sched: remove SYNC_WAKEUPS feature | From | Mike Galbraith <> | Date | Thu, 11 Mar 2010 11:03:37 +0100 |
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sched: remove SYNC_WAKEUPS feature
Sync wakeups are critical functionality with a long history. Remove it, we don't need the branch or icache footprint.
Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission>
--- kernel/sched.c | 3 --- kernel/sched_features.h | 8 -------- 2 files changed, 11 deletions(-)
Index: linux-2.6/kernel/sched.c =================================================================== --- linux-2.6.orig/kernel/sched.c +++ linux-2.6/kernel/sched.c @@ -2369,9 +2369,6 @@ static int try_to_wake_up(struct task_st unsigned long flags; struct rq *rq, *orig_rq; - if (!sched_feat(SYNC_WAKEUPS)) - wake_flags &= ~WF_SYNC; - this_cpu = get_cpu(); smp_wmb(); Index: linux-2.6/kernel/sched_features.h =================================================================== --- linux-2.6.orig/kernel/sched_features.h +++ linux-2.6/kernel/sched_features.h @@ -17,14 +17,6 @@ SCHED_FEAT(START_DEBIT, 1) SCHED_FEAT(WAKEUP_PREEMPT, 1) /* - * Use the SYNC wakeup hint, pipes and the likes use this to indicate - * the remote end is likely to consume the data we just wrote, and - * therefore has cache benefit from being placed on the same cpu, see - * also AFFINE_WAKEUPS. - */ -SCHED_FEAT(SYNC_WAKEUPS, 1) - -/* * Based on load and program behaviour, see if it makes sense to place * a newly woken task on the same cpu as the task that woke it -- * improve cache locality. Typically used with SYNC wakeups as
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