lkml.org 
[lkml]   [2017]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH V3 0/2] load_balance() fixes for affinity
From
Date
Hey Peter,


On 5/22/2017 9:52 AM, Peter Zijlstra wrote:
> On Thu, May 18, 2017 at 01:36:01PM -0600, Jeffrey Hugo wrote:
>
>> The group_imbalance path correctly sets the flag
>> to indicate the group can not be properly balanced due to affinity, but the
>> redo condition right after this branch incorrectly assumes that there may
>> be other cores with work to be pulled by considering cores outside of the
>> scheduling domain in question.
> So its been a while since I looked at any of this, but from a quick
> look, env->cpus appears to only be applied to group/balance masks.
>
> In which case, we can easily do something like the below. Did I miss
> something?
We have looked through and agree with your proposed change; however, we
would still need to mask out the dst_cpu when considering the redo path.
We will include this modification in the next patch set.
>
> ---
> kernel/sched/fair.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 219fe58e3023..1724e4433f89 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8104,7 +8104,7 @@ static int load_balance(int this_cpu, struct rq *this_rq,
> if (idle == CPU_NEWLY_IDLE)
> env.dst_grpmask = NULL;
>
> - cpumask_copy(cpus, cpu_active_mask);
> + cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask);
>
> schedstat_inc(sd->lb_count[idle]);
>

--
Qualcomm Datacenter Technologies as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

\
 
 \ /
  Last update: 2017-05-22 22:17    [W:0.470 / U:0.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site