Re: [patch 9/12] sched: remove WAKEUP_SYNC feature

From: Mike Galbraith
Date: Thu Mar 11 2010 - 05:00:01 EST



sched: remove WAKEUP_SYNC feature

This feature never earned it's keep, remove it.

Signed-off-by: Mike Galbraith <efault@xxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
LKML-Reference: <new-submission>

---
kernel/sched_fair.c | 4 ----
kernel/sched_features.h | 5 -----
2 files changed, 9 deletions(-)

Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -1657,7 +1657,6 @@ static void check_preempt_wakeup(struct
struct task_struct *curr = rq->curr;
struct sched_entity *se = &curr->se, *pse = &p->se;
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
- int sync = wake_flags & WF_SYNC;
int scale = cfs_rq->nr_running >= sched_nr_latency;

if (unlikely(rt_prio(p->prio)))
@@ -1690,9 +1689,6 @@ static void check_preempt_wakeup(struct
if (unlikely(curr->policy == SCHED_IDLE))
goto preempt;

- if (sched_feat(WAKEUP_SYNC) && sync)
- goto preempt;
-
if (!sched_feat(WAKEUP_PREEMPT))
return;

Index: linux-2.6/kernel/sched_features.h
===================================================================
--- linux-2.6.orig/kernel/sched_features.h
+++ linux-2.6/kernel/sched_features.h
@@ -23,11 +23,6 @@ SCHED_FEAT(WAKEUP_PREEMPT, 1)
SCHED_FEAT(ASYM_GRAN, 1)

/*
- * Always wakeup-preempt SYNC wakeups, see SYNC_WAKEUPS.
- */
-SCHED_FEAT(WAKEUP_SYNC, 0)
-
-/*
* 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


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