linux-kernel - [PATCH 3/7] RT: Only consider online CPUs when pushing rt tasks

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Date:	Thu, 11 Oct 2007 17:59:59 -0400
From:	Gregory Haskins <ghaskins@...ell.com>
To:	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-rt-users <linux-rt-users@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Gregory Haskins <ghaskins@...ell.com>
Subject: [PATCH 3/7] RT: Only consider online CPUs when pushing rt tasks

task->cpus_allowed can have bit positions that are set for CPUs that are
not currently online.  So we optimze our search by ANDing against the online
set.

Signed-off-by: Gregory Haskins <ghaskins@...ell.com>
---

 kernel/sched.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index 24b38b4..0ca3905 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1510,10 +1510,14 @@ static int push_rt_task(struct rq *this_rq)
 
 	/* Only try this algorithm three times */
 	for (tries = 0; tries < 3; tries++) {
+		cpumask_t mask;
+
+		cpus_and(mask, cpu_online_map, next_task->cpus_allowed);
+
 		/*
 		 * Scan each rq for the lowest prio.
 		 */
-		for_each_cpu_mask(cpu, next_task->cpus_allowed) {
+		for_each_cpu_mask(cpu, mask) {
 			struct rq *rq = &per_cpu(runqueues, cpu);
 
 			if (cpu == smp_processor_id())

-
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