On Fri, Jun 06, 2014 at 01:16:23PM +0200, Mike Galbraith wrote: > On Fri, 2014-06-06 at 12:15 +0200, Peter Zijlstra wrote: > > > > --- a/kernel/sched/fair.c Fri Jun 6 12:37:37 2014 > > > +++ b/kernel/sched/fair.c Fri Jun 6 14:32:34 2014 > > > @@ -5051,7 +5051,7 @@ task_hot(struct task_struct *p, u64 now) > > > /* > > > * Buddy candidates are cache hot: > > > */ > > > - if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running && > > > + if (sched_feat(CACHE_HOT_BUDDY) && task_rq(p)->nr_running && > > > (&p->se == cfs_rq_of(&p->se)->next || > > > &p->se == cfs_rq_of(&p->se)->last)) > > > return 1; > > > > That does appear to make more sense indeed, seeing how buddies are pairs > > of tasks, so protecting a lone task doesn't make sense. > > > > > > Mike, how did you intend this code to work? > > IIRC, this_rq()->nr_running was to say if we're idle, we don't care that > it's last/next, pull it. Not sure I'm the one who did that, but could > be, I didn't look. >
commit f685ceacab07d3f6c236f04803e2f2f0dbcc5afb
Author: Mike Galbraith <efa...@gmx.de>
Date: Fri Oct 23 23:09:22 2009 +0200
sched: Strengthen buddies and mitigate buddy induced latencies
...
- if (sched_feat(CACHE_HOT_BUDDY) &&
+ if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
(&p->se == cfs_rq_of(&p->se)->next ||
&p->se == cfs_rq_of(&p->se)->last))
Yeah, was you ;-)
OK, so we want dst_rq. Thanks!
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