[PATCH] sched: filter affine wakeups
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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>
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 @@
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;