Messages in this thread | | | Date | Mon, 21 Jan 2013 17:22:41 +0800 | From | Michael Wang <> | Subject | Re: [RFC PATCH 0/2] sched: simplify the select_task_rq_fair() |
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On 01/21/2013 05:09 PM, Mike Galbraith wrote: > On Mon, 2013-01-21 at 15:45 +0800, Michael Wang wrote: >> 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? > > No, it does not.
Hmm...what have changed now compared to the old logical?
May be I missed some thing, well, I think I need to find a machine which could reproduce the issue firstly.
Regards, Michael Wang
> >> >> 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: > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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