From: Vlastimil Babka <vbabka@suse.cz>
To: David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@suse.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [patch 1/2] mm, zone: track number of pages in free area by migratetype
Date: Thu, 17 Nov 2016 18:04:08 +0100 [thread overview]
Message-ID: <49ed7412-eab7-4d8d-c6df-fdf76d98da4d@suse.cz> (raw)
In-Reply-To: <alpine.DEB.2.10.1611161731350.17379@chino.kir.corp.google.com>
On 11/17/2016 02:32 AM, David Rientjes wrote:
> Each zone's free_area tracks the number of free pages for all free lists.
> This does not allow the number of free pages for a specific migratetype
> to be determined without iterating its free list.
>
> An upcoming change will use this information to preclude doing async
> memory compaction when the number of MIGRATE_UNMOVABLE pageblocks is
> below a certain threshold.
>
> The total number of free pages is still tracked, however, to not make
> zone_watermark_ok() more expensive. Reading /proc/pagetypeinfo, however,
> is faster.
Yeah I've already seen a case with /proc/pagetypeinfo causing soft
lockups due to high number of iterations...
> This patch introduces no functional change and increases the amount of
> per-zone metadata at worst by 48 bytes per memory zone (when CONFIG_CMA
> and CONFIG_MEMORY_ISOLATION are enabled).
Isn't it 48 bytes per zone and order?
> Signed-off-by: David Rientjes <rientjes@google.com>
I'd be for this if there are no performance regressions. It affects hot
paths and increases cache footprint. I think at least some allocator
intensive microbenchmark should be used.
Vlastimil
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next prev parent reply other threads:[~2016-11-17 17:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-17 1:32 David Rientjes
2016-11-17 1:32 ` [patch 2/2] mm, compaction: avoid async compaction if most free memory is ineligible David Rientjes
2016-11-17 17:04 ` Vlastimil Babka [this message]
2016-11-17 22:11 ` [patch 1/2] mm, zone: track number of pages in free area by migratetype David Rientjes
2016-11-18 20:58 ` Vlastimil Babka
2016-11-30 0:16 ` [patch v2 1/2] mm, zone: track number of movable free pages David Rientjes
2016-11-30 0:16 ` [patch v2 2/2] mm, compaction: avoid async compaction if most free memory is ineligible David Rientjes
2016-11-30 7:34 ` [patch v2 1/2] mm, zone: track number of movable free pages Vlastimil Babka
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