From: Peter Zijlstra <peterz@infradead.org>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 5/8] sched: Favour moving tasks towards the preferred node
Date: Fri, 28 Jun 2013 11:04:47 +0200 [thread overview]
Message-ID: <20130628090447.GD28407@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20130628081120.GE17195@linux.vnet.ibm.com>
On Fri, Jun 28, 2013 at 01:41:20PM +0530, Srikar Dronamraju wrote:
Please trim your replies.
> > +/* Returns true if the destination node has incurred more faults */
> > +static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
> > +{
> > + int src_nid, dst_nid;
> > +
> > + if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
> > + return false;
> > +
> > + src_nid = cpu_to_node(env->src_cpu);
> > + dst_nid = cpu_to_node(env->dst_cpu);
> > +
> > + if (src_nid == dst_nid)
> > + return false;
> > +
> > + if (p->numa_migrate_seq < sysctl_numa_balancing_settle_count &&
>
> Lets say even if the numa_migrate_seq is greater than settle_count but running
> on a wrong node, then shouldnt this be taken as a good opportunity to
> move the task?
I think that's what its doing; so this stmt says; if seq is large and
we're trying to move to the 'right' node; move it noaw.
> > + p->numa_preferred_nid == dst_nid)
> > + return true;
> > +
> > + return false;
> > +}
> > +
> > +
> > /*
> > * can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
> > */
> > @@ -3945,10 +3977,14 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
> >
> > /*
> > * Aggressive migration if:
> > - * 1) task is cache cold, or
> > - * 2) too many balance attempts have failed.
> > + * 1) destination numa is preferred
> > + * 2) task is cache cold, or
> > + * 3) too many balance attempts have failed.
> > */
> >
> > + if (migrate_improves_locality(p, env))
> > + return 1;
>
> Shouldnt this be under tsk_cache_hot check?
>
> If the task is cache hot, then we would have to update the corresponding schedstat
> metrics.
No; you want migrate_degrades_locality() to be like task_hot(). You want
to _always_ migrate tasks towards better locality irrespective of local
cache hotness.
next prev parent reply other threads:[~2013-06-28 9:04 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-26 14:37 [PATCH 0/6] Basic scheduler support for automatic NUMA balancing Mel Gorman
2013-06-26 14:38 ` [PATCH 1/8] mm: numa: Document automatic NUMA balancing sysctls Mel Gorman
2013-06-26 14:38 ` [PATCH 2/8] sched: Track NUMA hinting faults on per-node basis Mel Gorman
2013-06-27 15:57 ` Peter Zijlstra
2013-06-28 12:22 ` Mel Gorman
2013-06-28 6:08 ` Srikar Dronamraju
2013-06-28 8:56 ` Peter Zijlstra
2013-06-28 12:30 ` Mel Gorman
2013-06-26 14:38 ` [PATCH 3/8] sched: Select a preferred node with the most numa hinting faults Mel Gorman
2013-06-28 6:14 ` Srikar Dronamraju
2013-06-28 8:59 ` Peter Zijlstra
2013-06-28 10:24 ` Srikar Dronamraju
2013-06-28 12:33 ` Mel Gorman
2013-06-26 14:38 ` [PATCH 4/8] sched: Update NUMA hinting faults once per scan Mel Gorman
2013-06-28 6:32 ` Srikar Dronamraju
2013-06-28 9:01 ` Peter Zijlstra
2013-06-26 14:38 ` [PATCH 5/8] sched: Favour moving tasks towards the preferred node Mel Gorman
2013-06-27 14:52 ` Peter Zijlstra
2013-06-27 14:53 ` Peter Zijlstra
2013-06-28 13:00 ` Mel Gorman
2013-06-27 16:01 ` Peter Zijlstra
2013-06-28 13:01 ` Mel Gorman
2013-06-27 16:11 ` Peter Zijlstra
2013-06-28 13:45 ` Mel Gorman
2013-06-28 15:10 ` Peter Zijlstra
2013-06-28 8:11 ` Srikar Dronamraju
2013-06-28 9:04 ` Peter Zijlstra [this message]
2013-06-28 10:07 ` Srikar Dronamraju
2013-06-28 10:24 ` Peter Zijlstra
2013-06-28 13:51 ` Mel Gorman
2013-06-28 17:14 ` Srikar Dronamraju
2013-06-28 17:34 ` Mel Gorman
2013-06-28 17:44 ` Srikar Dronamraju
2013-06-26 14:38 ` [PATCH 6/8] sched: Reschedule task on preferred NUMA node once selected Mel Gorman
2013-06-27 14:54 ` Peter Zijlstra
2013-06-28 13:54 ` Mel Gorman
2013-07-02 12:06 ` Srikar Dronamraju
2013-07-02 16:29 ` Mel Gorman
2013-07-02 18:17 ` Peter Zijlstra
2013-07-06 6:44 ` Srikar Dronamraju
2013-07-06 10:47 ` Peter Zijlstra
2013-07-02 18:15 ` Peter Zijlstra
2013-07-03 9:50 ` Peter Zijlstra
2013-07-03 15:28 ` Mel Gorman
2013-07-03 18:46 ` Peter Zijlstra
2013-06-26 14:38 ` [PATCH 7/8] sched: Split accounting of NUMA hinting faults that pass two-stage filter Mel Gorman
2013-06-27 14:56 ` Peter Zijlstra
2013-06-28 14:00 ` Mel Gorman
2013-06-28 7:00 ` Srikar Dronamraju
2013-06-28 9:36 ` Peter Zijlstra
2013-06-28 10:12 ` Srikar Dronamraju
2013-06-28 10:33 ` Peter Zijlstra
2013-06-28 14:29 ` Mel Gorman
2013-06-28 15:12 ` Peter Zijlstra
2013-06-26 14:38 ` [PATCH 8/8] sched: Increase NUMA PTE scanning when a new preferred node is selected Mel Gorman
2013-06-27 14:59 ` [PATCH 0/6] Basic scheduler support for automatic NUMA balancing Peter Zijlstra
2013-06-28 13:54 ` Srikar Dronamraju
2013-07-01 5:39 ` Srikar Dronamraju
2013-07-01 8:43 ` Mel Gorman
2013-07-02 5:28 ` Srikar Dronamraju
2013-07-02 7:46 ` Peter Zijlstra
2013-07-02 8:55 ` Peter Zijlstra
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