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[PATCH] sched: allow the load to grow upto its cpu_power 

Don't pull tasks from a group if that would cause the group's total load to
drop below its total cpu_power (ie.  cause the group to start going idle).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Siddha, Suresh B 2005-09-10 00:26:21 -07:00 committed by Linus Torvalds
parent fa3b6ddc3f
commit 0c117f1b4d
1 changed files with 7 additions and 2 deletions
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9
kernel/sched.c
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@ -1910,6 +1910,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
{
struct sched_group *busiest = NULL, *this = NULL, *group = sd->groups;
unsigned long max_load, avg_load, total_load, this_load, total_pwr;
unsigned long max_pull;
int load_idx;
max_load = this_load = total_load = total_pwr = 0;
@ -1959,7 +1960,7 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
group = group->next;
} while (group != sd->groups);
if (!busiest || this_load >= max_load)
if (!busiest || this_load >= max_load || max_load <= SCHED_LOAD_SCALE)
goto out_balanced;
avg_load = (SCHED_LOAD_SCALE * total_load) / total_pwr;
@ -1979,8 +1980,12 @@ find_busiest_group(struct sched_domain *sd, int this_cpu,
* by pulling tasks to us. Be careful of negative numbers as they'll
* appear as very large values with unsigned longs.
*/
/* Don't want to pull so many tasks that a group would go idle */
max_pull = min(max_load - avg_load, max_load - SCHED_LOAD_SCALE);
/* How much load to actually move to equalise the imbalance */
*imbalance = min((max_load - avg_load) * busiest->cpu_power,
*imbalance = min(max_pull * busiest->cpu_power,
(avg_load - this_load) * this->cpu_power)
/ SCHED_LOAD_SCALE;