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From: Johannes Weiner <hannes@cmpxchg.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Linux-FSDevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines
Date: Thu, 10 Jul 2014 08:06:15 -0400	[thread overview]
Message-ID: <20140710120615.GJ29639@cmpxchg.org> (raw)
In-Reply-To: <1404893588-21371-3-git-send-email-mgorman@suse.de>

On Wed, Jul 09, 2014 at 09:13:04AM +0100, Mel Gorman wrote:
> The arrangement of struct zone has changed over time and now it has reached the
> point where there is some inappropriate sharing going on. On x86-64 for example
> 
> o The zone->node field is shared with the zone lock and zone->node is accessed
>   frequently from the page allocator due to the fair zone allocation policy.
> o span_seqlock is almost never used by shares a line with free_area
> o Some zone statistics share a cache line with the LRU lock so reclaim-intensive
>   and allocator-intensive workloads can bounce the cache line on a stat update
> 
> This patch rearranges struct zone to put read-only and read-mostly fields
> together and then splits the page allocator intensive fields, the zone
> statistics and the page reclaim intensive fields into their own cache
> lines. Note that the type of lowmem_reserve changes due to the watermark
> calculations being signed and avoiding a signed/unsigned conversion there.
> 
> On the test configuration I used the overall size of struct zone shrunk
> by one cache line. On smaller machines, this is not likely to be noticable.
> However, on a 4-node NUMA machine running tiobench the system CPU overhead
> is reduced by this patch.
> 
>           3.16.0-rc3  3.16.0-rc3
>              vanillarearrange-v5r9
> User          746.94      759.78
> System      65336.22    58350.98
> Elapsed     27553.52    27282.02
> 
> Signed-off-by: Mel Gorman <mgorman@suse.de>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Linux-FSDevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines
Date: Thu, 10 Jul 2014 08:06:15 -0400	[thread overview]
Message-ID: <20140710120615.GJ29639@cmpxchg.org> (raw)
In-Reply-To: <1404893588-21371-3-git-send-email-mgorman@suse.de>

On Wed, Jul 09, 2014 at 09:13:04AM +0100, Mel Gorman wrote:
> The arrangement of struct zone has changed over time and now it has reached the
> point where there is some inappropriate sharing going on. On x86-64 for example
> 
> o The zone->node field is shared with the zone lock and zone->node is accessed
>   frequently from the page allocator due to the fair zone allocation policy.
> o span_seqlock is almost never used by shares a line with free_area
> o Some zone statistics share a cache line with the LRU lock so reclaim-intensive
>   and allocator-intensive workloads can bounce the cache line on a stat update
> 
> This patch rearranges struct zone to put read-only and read-mostly fields
> together and then splits the page allocator intensive fields, the zone
> statistics and the page reclaim intensive fields into their own cache
> lines. Note that the type of lowmem_reserve changes due to the watermark
> calculations being signed and avoiding a signed/unsigned conversion there.
> 
> On the test configuration I used the overall size of struct zone shrunk
> by one cache line. On smaller machines, this is not likely to be noticable.
> However, on a 4-node NUMA machine running tiobench the system CPU overhead
> is reduced by this patch.
> 
>           3.16.0-rc3  3.16.0-rc3
>              vanillarearrange-v5r9
> User          746.94      759.78
> System      65336.22    58350.98
> Elapsed     27553.52    27282.02
> 
> Signed-off-by: Mel Gorman <mgorman@suse.de>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

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  reply	other threads:[~2014-07-10 12:06 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-07-09  8:13 [PATCH 0/5] Reduce sequential read overhead Mel Gorman
2014-07-09  8:13 ` Mel Gorman
2014-07-09  8:13 ` [PATCH 1/6] mm: pagemap: Avoid unnecessary overhead when tracepoints are deactivated Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:01   ` Johannes Weiner
2014-07-10 12:01     ` Johannes Weiner
2014-07-09  8:13 ` [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:06   ` Johannes Weiner [this message]
2014-07-10 12:06     ` Johannes Weiner
2014-07-09  8:13 ` [PATCH 3/6] mm: Move zone->pages_scanned into a vmstat counter Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:08   ` Johannes Weiner
2014-07-10 12:08     ` Johannes Weiner
2014-07-09  8:13 ` [PATCH 4/6] mm: vmscan: Only update per-cpu thresholds for online CPU Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:09   ` Johannes Weiner
2014-07-10 12:09     ` Johannes Weiner
2014-07-09  8:13 ` [PATCH 5/6] mm: page_alloc: Abort fair zone allocation policy when remotes nodes are encountered Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:14   ` Johannes Weiner
2014-07-10 12:14     ` Johannes Weiner
2014-07-10 12:44     ` Mel Gorman
2014-07-10 12:44       ` Mel Gorman
2014-07-09  8:13 ` [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation policy Mel Gorman
2014-07-09  8:13   ` Mel Gorman
2014-07-10 12:18   ` Johannes Weiner
2014-07-10 12:18     ` Johannes Weiner
2014-08-08 15:27   ` Vlastimil Babka
2014-08-08 15:27     ` Vlastimil Babka
2014-08-11 12:12     ` Mel Gorman
2014-08-11 12:12       ` Mel Gorman
2014-08-11 12:34       ` Vlastimil Babka
2014-08-11 12:34         ` Vlastimil Babka
2014-09-02 14:01         ` Johannes Weiner
2014-09-02 14:01           ` Johannes Weiner
2014-09-05 10:14           ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP Mel Gorman
2014-09-05 10:14             ` Mel Gorman
2014-09-07  6:32             ` Leon Romanovsky
2014-09-07  6:32               ` Leon Romanovsky
2014-09-08 11:57               ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Mel Gorman
2014-09-08 11:57                 ` Mel Gorman
2014-09-09  8:17                 ` Leon Romanovsky
2014-09-09 19:53                 ` Andrew Morton
2014-09-09 19:53                   ` Andrew Morton
2014-09-10  9:16                   ` Mel Gorman
2014-09-10  9:16                     ` Mel Gorman
2014-09-10 20:32                     ` Johannes Weiner
2014-09-10 20:32                       ` Johannes Weiner
  -- strict thread matches above, loose matches on Subject: below --
2014-06-25  7:58 [PATCH 0/6] Improve sequential read throughput v2 Mel Gorman
2014-06-25  7:58 ` [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines Mel Gorman
2014-06-25  7:58   ` Mel Gorman

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