linux-kernel - Re: [PATCH 3/8] sched: Select a preferred node with the most numa hinting faults

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Message-ID: <20130628102404.GE8362@linux.vnet.ibm.com>
Date:	Fri, 28 Jun 2013 15:54:04 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Mel Gorman <mgorman@...e.de>, Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/8] sched: Select a preferred node with the most numa
 hinting faults

> > >  
> > >  	struct rcu_head rcu;
> > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > > index f332ec0..019baae 100644
> > > --- a/kernel/sched/core.c
> > > +++ b/kernel/sched/core.c
> > > @@ -1593,6 +1593,7 @@ static void __sched_fork(struct task_struct *p)
> > >  	p->numa_scan_seq = p->mm ? p->mm->numa_scan_seq : 0;
> > >  	p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0;
> > >  	p->numa_scan_period = sysctl_numa_balancing_scan_delay;
> > > +	p->numa_preferred_nid = -1;
> > 
> > Though we may not want to inherit faults, I think the tasks generally
> > share pages with their siblings, parent. So will it make sense to
> > inherit the preferred node?
> 
> One of the patches I have locally wipes the numa state on exec(). I
> think we want to do that if we're going to think about inheriting stuff.
> 
> 

Agree, if we inherit the preferred node, we would have to reset on exec.
Since we have to reset the numa_faults also on exec, the reset of
preferred node can go in task_numa_free

-- 
Thanks and Regards
Srikar Dronamraju

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