On 01/21/2013 03:09 PM, Mike Galbraith wrote:
> On Mon, 2013-01-21 at 07:42 +0100, Mike Galbraith wrote:
>> On Mon, 2013-01-21 at 13:07 +0800, Michael Wang wrote:
>
>>> May be we could try change this back to the old way later, after the aim
>>> 7 test on my server.
>>
>> Yeah, something funny is going on.
>
> Never entering balance path kills the collapse. Asking wake_affine()
> wrt the pull as before, but allowing us to continue should no idle cpu
> be found, still collapsed. So the source of funny behavior is indeed in
> balance_path.
Below patch based on the patch set could help to avoid enter balance path
if affine_sd could be found, just like the old logical, would you like to
take a try and see whether it could help fix the collapse?
Regards,
Michael Wang
---
kernel/sched/fair.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d600708..4e95bb0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3297,6 +3297,8 @@ next:
sg = sg->next;
} while (sg != sd->groups);
}
+
+ return -1;
done:
return target;
}
@@ -3349,7 +3351,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag,
int wake_flags)
* some cases.
*/
new_cpu = select_idle_sibling(p, prev_cpu);
- if (idle_cpu(new_cpu))
+ if (new_cpu != -1)
goto unlock;
/*
@@ -3363,15 +3365,15 @@ select_task_rq_fair(struct task_struct *p, int sd_flag,
int wake_flags)
goto balance_path;
new_cpu = select_idle_sibling(p, cpu);
- if (!idle_cpu(new_cpu))
- goto balance_path;
-
/*
* Invoke wake_affine() finally since it is no doubt a
* performance killer.
*/
- if (wake_affine(sbm->affine_map[prev_cpu], p, sync))
- goto unlock;
+ if (new_cpu == -1 ||
+ !wake_affine(sbm->affine_map[prev_cpu], p, sync))
+ new_cpu = prev_cpu;
+
+ goto unlock;
}
balance_path:
--
1.7.4.1
>
> -Mike
>
> --
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