[PATCH] sched: no aggressive idle balancing

Remove the very aggressive idle stuff that has recently gone into 2.6 - it is
going against the direction we are trying to go.  Hopefully we can regain
performance through other methods.

Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 2 insertions, 19 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5ae3568eed0b..396724a2519f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -414,22 +414,6 @@ static inline runqueue_t *this_rq_lock(void)
         return rq;
 }
 
-#ifdef CONFIG_SCHED_SMT
-static int cpu_and_siblings_are_idle(int cpu)
-{
-        int sib;
-        for_each_cpu_mask(sib, cpu_sibling_map[cpu]) {
-                if (idle_cpu(sib))
-                        continue;
-                return 0;
-        }
-
-        return 1;
-}
-#else
-#define cpu_and_siblings_are_idle(A) idle_cpu(A)
-#endif
-
 #ifdef CONFIG_SCHEDSTATS
 /*
  * Called when a process is dequeued from the active array and given
@@ -1652,12 +1636,11 @@ int can_migrate_task(task_t *p, runqueue_t *rq, int this_cpu,
 
         /*
          * Aggressive migration if:
-         * 1) the [whole] cpu is idle, or
+         * 1) task is cache cold, or
          * 2) too many balance attempts have failed.
          */
 
-        if (cpu_and_siblings_are_idle(this_cpu) || \
-                        sd->nr_balance_failed > sd->cache_nice_tries)
+        if (sd->nr_balance_failed > sd->cache_nice_tries)
                 return 1;
 
         if (task_hot(p, rq->timestamp_last_tick, sd))