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>
next prev parent reply other threads:[~2014-07-10 12:06 UTC|newest]
Thread overview: 25+ 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 ` [PATCH 1/6] mm: pagemap: Avoid unnecessary overhead when tracepoints are deactivated Mel Gorman
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
2014-07-10 12:06 ` Johannes Weiner [this message]
2014-07-09 8:13 ` [PATCH 3/6] mm: Move zone->pages_scanned into a vmstat counter Mel Gorman
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
2014-07-10 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
2014-07-10 12:14 ` Johannes Weiner
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
2014-07-10 12:18 ` Johannes Weiner
2014-08-08 15:27 ` Vlastimil Babka
2014-08-11 12:12 ` Mel Gorman
2014-08-11 12:34 ` Vlastimil Babka
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
2014-09-07 6:32 ` Leon Romanovsky
2014-09-08 11:57 ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Mel Gorman
2014-09-09 19:53 ` Andrew Morton
2014-09-10 9:16 ` Mel Gorman
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
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