From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>,
Konstantin Khlebnikov <khlebnikov@openvz.org>,
linux-mm@kvack.org, Mel Gorman <mel@csn.ul.ie>
Subject: Re: [PATCH 3/3] mm: take pagevecs off reclaim stack
Date: Sat, 31 Dec 2011 23:18:15 -0800 (PST) [thread overview]
Message-ID: <alpine.LSU.2.00.1112312302010.18500@eggly.anvils> (raw)
In-Reply-To: <20111229195917.13f15974.akpm@linux-foundation.org>
On Thu, 29 Dec 2011, Andrew Morton wrote:
>
> This is not all some handwavy theoretical thing either. If we've gone
> and introduced serious latency issues, people *will* hit them and treat
> it as a regression.
Sure, though the worst I've seen so far (probably haven't been trying
hard enough yet, I need to go for THPs) is 39 pages freed in one call.
Regression? Well, any bad latency would already have been there on
the gathering side.
>
> Now, a way out here is to remove lumpy reclaim (please). And make the
> problem not come back by promising to never call putback_lru_pages(lots
> of pages) (how do we do this?).
We can very easily put a counter in it, doing a spin_unlock_irq every
time we hit the max. Nothing prevents that, it's just an excrescence
I'd have preferred to omit and have not today implemented.
>
> So I think the best way ahead here is to distribute this patch in the
> same release in which we remove lumpy reclaim (pokes Mel).
I'm sure there are better reasons for removing lumpy than that I posted
a patch which happened to remove some limitation. No need to poke Mel
on my behalf!
Hugh
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next prev parent reply other threads:[~2012-01-01 7:18 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-29 4:32 [PATCH 0/3] mm: three minor vmscan improvements Hugh Dickins
2011-12-29 4:35 ` [PATCH 1/3] mm: test PageSwapBacked in lumpy reclaim Hugh Dickins
2011-12-29 5:06 ` KOSAKI Motohiro
2012-01-04 1:23 ` Minchan Kim
2012-01-05 6:03 ` KAMEZAWA Hiroyuki
2011-12-29 4:36 ` [PATCH 2/3] mm: cond_resched in scan_mapping_unevictable_pages Hugh Dickins
2011-12-29 5:14 ` KOSAKI Motohiro
2011-12-29 5:48 ` Hugh Dickins
2011-12-29 22:46 ` Hugh Dickins
2011-12-29 4:39 ` [PATCH 3/3] mm: take pagevecs off reclaim stack Hugh Dickins
2011-12-29 5:42 ` KOSAKI Motohiro
2011-12-29 11:18 ` Konstantin Khlebnikov
2011-12-29 22:20 ` Hugh Dickins
2011-12-29 22:55 ` Andrew Morton
2011-12-29 23:27 ` Hugh Dickins
2011-12-30 0:24 ` KOSAKI Motohiro
2011-12-30 1:55 ` Hugh Dickins
2011-12-30 3:59 ` Andrew Morton
2011-12-30 15:51 ` Mel Gorman
2012-01-01 7:18 ` Hugh Dickins [this message]
2012-01-03 23:12 ` Andrew Morton
2012-01-03 23:17 ` KOSAKI Motohiro
2012-01-03 23:29 ` Andrew Morton
2012-01-04 0:03 ` KOSAKI Motohiro
2012-01-04 3:22 ` Hugh Dickins
2012-01-04 20:20 ` Andrew Morton
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