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authorakpm@osdl.org <akpm@osdl.org>2006-01-12 01:05:32 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-12 09:08:50 -0800
commitd7102e95b7b9c00277562c29aad421d2d521c5f6 (patch)
tree3ad3d94c329095962c6cd6dcea41e1ccf2db5a7e
parent198e2f181163233b379dc7ce8a6d7516b84042e7 (diff)
downloadop-kernel-dev-d7102e95b7b9c00277562c29aad421d2d521c5f6.zip
op-kernel-dev-d7102e95b7b9c00277562c29aad421d2d521c5f6.tar.gz
[PATCH] sched: filter affine wakeups
) From: Nick Piggin <nickpiggin@yahoo.com.au> Track the last waker CPU, and only consider wakeup-balancing if there's a match between current waker CPU and the previous waker CPU. This ensures that there is some correlation between two subsequent wakeup events before we move the task. Should help random-wakeup workloads on large SMP systems, by reducing the migration attempts by a factor of nr_cpus. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--include/linux/sched.h5
-rw-r--r--kernel/sched.c10
2 files changed, 13 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5d6b922..b5ef92a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -696,9 +696,12 @@ struct task_struct {
int lock_depth; /* BKL lock depth */
-#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
+#if defined(CONFIG_SMP)
+ int last_waker_cpu; /* CPU that last woke this task up */
+#if defined(__ARCH_WANT_UNLOCKED_CTXSW)
int oncpu;
#endif
+#endif
int prio, static_prio;
struct list_head run_list;
prio_array_t *array;
diff --git a/kernel/sched.c b/kernel/sched.c
index 98461de..c9dec2a 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1290,6 +1290,9 @@ static int try_to_wake_up(task_t *p, unsigned int state, int sync)
}
}
+ if (p->last_waker_cpu != this_cpu)
+ goto out_set_cpu;
+
if (unlikely(!cpu_isset(this_cpu, p->cpus_allowed)))
goto out_set_cpu;
@@ -1360,6 +1363,8 @@ out_set_cpu:
cpu = task_cpu(p);
}
+ p->last_waker_cpu = this_cpu;
+
out_activate:
#endif /* CONFIG_SMP */
if (old_state == TASK_UNINTERRUPTIBLE) {
@@ -1441,9 +1446,12 @@ void fastcall sched_fork(task_t *p, int clone_flags)
#ifdef CONFIG_SCHEDSTATS
memset(&p->sched_info, 0, sizeof(p->sched_info));
#endif
-#if defined(CONFIG_SMP) && defined(__ARCH_WANT_UNLOCKED_CTXSW)
+#if defined(CONFIG_SMP)
+ p->last_waker_cpu = cpu;
+#if defined(__ARCH_WANT_UNLOCKED_CTXSW)
p->oncpu = 0;
#endif
+#endif
#ifdef CONFIG_PREEMPT
/* Want to start with kernel preemption disabled. */
task_thread_info(p)->preempt_count = 1;
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