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sched: fix MC/HT scheduler optimization, without breaking the FUZZ logic.

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First fix the check
	if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task)
with this
	if (*imbalance < busiest_load_per_task)

As the current check is always false for nice 0 tasks (as
SCHED_LOAD_SCALE_FUZZ is same as busiest_load_per_task for nice 0
tasks).

With the above change, imbalance was getting reset to 0 in the corner
case condition, making the FUZZ logic fail. Fix it by not corrupting the
imbalance and change the imbalance, only when it finds that the HT/MC
optimization is needed.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Suresh Siddha 2007-09-05 14:32:48 +02:00 committed by Ingo Molnar
parent b21010ed64
commit 7fd0d2dde9
1 changed files with 3 additions and 5 deletions
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8
kernel/sched.c
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@ -2512,7 +2512,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
* a think about bumping its value to force at least one task to be
* moved
*/
if (*imbalance + SCHED_LOAD_SCALE_FUZZ < busiest_load_per_task) {
if (*imbalance < busiest_load_per_task) {
unsigned long tmp, pwr_now, pwr_move;
unsigned int imbn;
@ -2564,10 +2564,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
pwr_move /= SCHED_LOAD_SCALE;
/* Move if we gain throughput */
if (pwr_move <= pwr_now)
goto out_balanced;
*imbalance = busiest_load_per_task;
if (pwr_move > pwr_now)
*imbalance = busiest_load_per_task;
}
return busiest;