From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: mgorman@suse.de
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] mm: page allocator: Reconsider zones for allocation after direct reclaim
Date: Thu, 21 Jul 2011 18:35:40 +0900 [thread overview]
Message-ID: <4E27F2EC.2010902@jp.fujitsu.com> (raw)
In-Reply-To: <20110714061049.GK7529@suse.de>
Hi
>> So, I think we don't need to care zonelist, just kswapd turn off
>> their own node.
>
> I don't understand what you mean by this.
This was the answer of following your comments.
> Instead, couldn't we turn zlc->fullzones off from kswapd?
> >
> > Which zonelist should it clear (there are two)
I mean, buddy list is belong to zone, not zonelist. therefore, kswapd
don't need to look up zonelist.
So, I'd suggest either following way,
- use direct reclaim path, but only clear a zlc bit of zones in reclaimed zonelist, not all. or
- use kswapd and only clear a zlc bit at kswap exiting balance_pgdat
I'm prefer to add a branch to slowpath (ie reclaim path) rather than fast path.
>> And, just curious, If we will have a proper zlc clear point, why
>> do we need to keep HZ timeout?
>
> Yes because we are not guaranteed to call direct reclaim either. Memory
> could be freed by a process exiting and I'd rather not add cost to
> the free path to find and clear all zonelists referencing the zone the
> page being freed belongs to.
Ok, it's good trade-off. I agree we need to keep HZ timeout.
WARNING: multiple messages have this Message-ID (diff)
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: mgorman@suse.de
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] mm: page allocator: Reconsider zones for allocation after direct reclaim
Date: Thu, 21 Jul 2011 18:35:40 +0900 [thread overview]
Message-ID: <4E27F2EC.2010902@jp.fujitsu.com> (raw)
In-Reply-To: <20110714061049.GK7529@suse.de>
Hi
>> So, I think we don't need to care zonelist, just kswapd turn off
>> their own node.
>
> I don't understand what you mean by this.
This was the answer of following your comments.
> Instead, couldn't we turn zlc->fullzones off from kswapd?
> >
> > Which zonelist should it clear (there are two)
I mean, buddy list is belong to zone, not zonelist. therefore, kswapd
don't need to look up zonelist.
So, I'd suggest either following way,
- use direct reclaim path, but only clear a zlc bit of zones in reclaimed zonelist, not all. or
- use kswapd and only clear a zlc bit at kswap exiting balance_pgdat
I'm prefer to add a branch to slowpath (ie reclaim path) rather than fast path.
>> And, just curious, If we will have a proper zlc clear point, why
>> do we need to keep HZ timeout?
>
> Yes because we are not guaranteed to call direct reclaim either. Memory
> could be freed by a process exiting and I'd rather not add cost to
> the free path to find and clear all zonelists referencing the zone the
> page being freed belongs to.
Ok, it's good trade-off. I agree we need to keep HZ timeout.
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next prev parent reply other threads:[~2011-07-21 9:35 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-11 13:01 [RFC PATCH 0/3] Reduce frequency of stalls due to zone_reclaim() on NUMA Mel Gorman
2011-07-11 13:01 ` Mel Gorman
2011-07-11 13:01 ` [PATCH 1/3] mm: vmscan: Do use use PF_SWAPWRITE from zone_reclaim Mel Gorman
2011-07-11 13:01 ` Mel Gorman
2011-07-12 9:27 ` Minchan Kim
2011-07-12 9:27 ` Minchan Kim
2011-07-12 9:40 ` KOSAKI Motohiro
2011-07-12 9:40 ` KOSAKI Motohiro
2011-07-12 9:55 ` Minchan Kim
2011-07-12 9:55 ` Minchan Kim
2011-07-12 15:43 ` Christoph Lameter
2011-07-12 15:43 ` Christoph Lameter
2011-07-13 10:40 ` Mel Gorman
2011-07-13 10:40 ` Mel Gorman
2011-07-12 10:14 ` Mel Gorman
2011-07-12 10:14 ` Mel Gorman
2011-07-13 0:34 ` KOSAKI Motohiro
2011-07-13 0:34 ` KOSAKI Motohiro
2011-07-11 13:01 ` [PATCH 2/3] mm: page allocator: Initialise ZLC for first zone eligible for zone_reclaim Mel Gorman
2011-07-11 13:01 ` Mel Gorman
2011-07-13 1:15 ` KOSAKI Motohiro
2011-07-13 1:15 ` KOSAKI Motohiro
2011-07-13 11:02 ` Mel Gorman
2011-07-13 11:02 ` Mel Gorman
2011-07-14 1:20 ` KOSAKI Motohiro
2011-07-14 1:20 ` KOSAKI Motohiro
2011-07-14 6:11 ` Mel Gorman
2011-07-14 6:11 ` Mel Gorman
2011-07-11 13:01 ` [PATCH 3/3] mm: page allocator: Reconsider zones for allocation after direct reclaim Mel Gorman
2011-07-11 13:01 ` Mel Gorman
2011-07-13 0:42 ` KOSAKI Motohiro
2011-07-13 0:42 ` KOSAKI Motohiro
2011-07-13 11:10 ` Mel Gorman
2011-07-13 11:10 ` Mel Gorman
2011-07-14 3:20 ` KOSAKI Motohiro
2011-07-14 3:20 ` KOSAKI Motohiro
2011-07-14 6:10 ` Mel Gorman
2011-07-14 6:10 ` Mel Gorman
2011-07-21 9:35 ` KOSAKI Motohiro [this message]
2011-07-21 9:35 ` KOSAKI Motohiro
2011-07-21 10:31 ` Mel Gorman
2011-07-21 10:31 ` Mel Gorman
2011-07-15 14:59 [PATCH 0/2] Reduce frequency of stalls due to zone_reclaim() on NUMA v2 Mel Gorman
2011-07-15 14:59 ` [PATCH 3/3] mm: page allocator: Reconsider zones for allocation after direct reclaim Mel Gorman
2011-07-15 14:59 ` Mel Gorman
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