linux-kernel - [tip:sched/core] sched: Remove SYNC

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Date:	Thu, 11 Mar 2010 18:33:05 GMT
From:	tip-bot for Mike Galbraith <efault@....de>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	a.p.zijlstra@...llo.nl, efault@....de, tglx@...utronix.de,
	mingo@...e.hu
Subject: [tip:sched/core] sched: Remove SYNC_WAKEUPS feature

Commit-ID:  c6ee36c423c3ed1fb86bb3eabba9fc256a300d16
Gitweb:     http://git.kernel.org/tip/c6ee36c423c3ed1fb86bb3eabba9fc256a300d16
Author:     Mike Galbraith <efault@....de>
AuthorDate: Thu, 11 Mar 2010 17:16:43 +0100
Committer:  Ingo Molnar <mingo@...e.hu>
CommitDate: Thu, 11 Mar 2010 18:32:53 +0100

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@....de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
LKML-Reference: <1268301817.6785.47.camel@...ge.simson.net>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
 kernel/sched.c          |    3 ---
 kernel/sched_features.h |    8 --------
 2 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 16559de..cc6dc8c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2369,9 +2369,6 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state,
 	unsigned long flags;
 	struct rq *rq;
 
-	if (!sched_feat(SYNC_WAKEUPS))
-		wake_flags &= ~WF_SYNC;
-
 	this_cpu = get_cpu();
 
 	smp_wmb();
diff --git a/kernel/sched_features.h b/kernel/sched_features.h
index 1cb7c47..f54b6f9 100644
--- a/kernel/sched_features.h
+++ b/kernel/sched_features.h
@@ -23,14 +23,6 @@ SCHED_FEAT(WAKEUP_PREEMPT, 1)
 SCHED_FEAT(ASYM_GRAN, 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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