[PATCH 12/12] sched: Simplify set_task_cpu()

From: Peter Zijlstra
Date: Wed Dec 16 2009 - 12:10:49 EST


Rearrange code a bit now that its a simpler function.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
kernel/sched.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -2034,11 +2034,8 @@ task_hot(struct task_struct *p, u64 now,
return delta < (s64)sysctl_sched_migration_cost;
}

-
void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
{
- int old_cpu = task_cpu(p);
-
#ifdef CONFIG_SCHED_DEBUG
/*
* We should never call set_task_cpu() on a blocked task,
@@ -2049,11 +2046,11 @@ void set_task_cpu(struct task_struct *p,

trace_sched_migrate_task(p, new_cpu);

- if (old_cpu != new_cpu) {
- p->se.nr_migrations++;
- perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS,
- 1, 1, NULL, 0);
- }
+ if (task_cpu(p) == new_cpu)
+ return;
+
+ p->se.nr_migrations++;
+ perf_sw_event(PERF_COUNT_SW_CPU_MIGRATIONS, 1, 1, NULL, 0);

__set_task_cpu(p, new_cpu);
}

--

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