From: Wanpeng Li <liwanp@linux.vnet.ibm.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v3 09/12] sched/numa: fix task scan rate adjustment
Date: Tue, 10 Dec 2013 16:49:35 +0800 [thread overview]
Message-ID: <52a6d5b4.48b13c0a.0edd.6b08SMTPIN_ADDED_BROKEN@mx.google.com> (raw)
In-Reply-To: <20131210082758.GC11295@suse.de>
On Tue, Dec 10, 2013 at 08:27:59AM +0000, Mel Gorman wrote:
>On Tue, Dec 10, 2013 at 01:44:35AM -0500, Naoya Horiguchi wrote:
>> Hi Wanpeng,
>>
>> On Sun, Dec 08, 2013 at 02:14:50PM +0800, Wanpeng Li wrote:
>> > commit 04bb2f947 (sched/numa: Adjust scan rate in task_numa_placement) calculate
>> > period_slot which should be used as base value of scan rate increase if remote
>> > access dominate. However, current codes forget to use it, this patch fix it.
>> >
>> > Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> > ---
>> > kernel/sched/fair.c | 2 +-
>> > 1 files changed, 1 insertions(+), 1 deletions(-)
>> >
>> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
>> > index 7073c76..b077f1b3 100644
>> > --- a/kernel/sched/fair.c
>> > +++ b/kernel/sched/fair.c
>> > @@ -1358,7 +1358,7 @@ static void update_task_scan_period(struct task_struct *p,
>> > */
>> > period_slot = DIV_ROUND_UP(diff, NUMA_PERIOD_SLOTS);
>> > ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared));
>> > - diff = (diff * ratio) / NUMA_PERIOD_SLOTS;
>> > + diff = (period_slot * ratio) / NUMA_PERIOD_SLOTS;
>> > }
>> >
>> > p->numa_scan_period = clamp(p->numa_scan_period + diff,
>>
>> It seems to me that the original code is correct, because the mathematical
>> meaning of this hunk is clear:
>>
>> diff = (diff calculated by local-remote ratio) * (private-shared ratio)
>>
>
>Thanks Naoya.
>
>The original code is as intended and was meant to scale the difference
>between the NUMA_PERIOD_THRESHOLD and local/remote ratio when adjusting
>the scan period. The period_slot recalculation can be dropped.
>
Thanks Mel's pointing out. ;-)
Regards,
Wanpeng Li
>--
>Mel Gorman
>SUSE Labs
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next prev parent reply other threads:[~2013-12-10 8:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-08 6:14 [PATCH v3 01/12] sched/numa: fix set cpupid on page migration twice against thp Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 02/12] sched/numa: drop idx field of task_numa_env struct Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 03/12] sched/numa: drop sysctl_numa_balancing_settle_count sysctl Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 04/12] sched/numa: use wrapper function task_node to get node which task is on Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 05/12] sched/numa: make numamigrate_isolate_page static Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 06/12] sched/numa: make numamigrate_update_ratelimit static Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 07/12] sched/numa: fix set cpupid on page migration twice against normal page Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 08/12] sched/numa: use wrapper function task_faults_idx to calculate index in group_faults Wanpeng Li
2013-12-08 6:14 ` [PATCH v3 09/12] sched/numa: fix task scan rate adjustment Wanpeng Li
2013-12-10 6:44 ` Naoya Horiguchi
2013-12-10 6:51 ` Wanpeng Li
2013-12-10 8:27 ` Mel Gorman
2013-12-10 8:49 ` Wanpeng Li [this message]
2013-12-08 6:14 ` [PATCH v3 10/12] sched/numa: fix record hinting faults check Wanpeng Li
2013-12-10 7:01 ` Naoya Horiguchi
2013-12-08 6:14 ` [PATCH v3 11/12] sched/numa: drop unnecessary variable in task_weight Wanpeng Li
2013-12-10 7:11 ` Naoya Horiguchi
2013-12-08 6:14 ` [PATCH v3 12/12] sched/numa: drop local 'ret' in task_numa_migrate() Wanpeng Li
2013-12-10 7:12 ` Naoya Horiguchi
2013-12-10 7:17 ` Wanpeng Li
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