From: Dave Hansen <dave.hansen@intel.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>, Kevin Hilman <khilman@linaro.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Paul Bolle <paul.bollee@gmail.com>,
Zlatko Calusic <zcalusic@bitsync.net>,
Andrew Morton <akpm@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: NUMA? bisected performance regression 3.11->3.12
Date: Thu, 21 Nov 2013 22:18:44 -0800 [thread overview]
Message-ID: <528EF744.8040607@intel.com> (raw)
In-Reply-To: <20131122052219.GL3556@cmpxchg.org>
On 11/21/2013 09:22 PM, Johannes Weiner wrote:
>> > It's a 8-socket/160-thread (one NUMA node per socket) system that is not
>> > under memory pressure during the test. The latencies are also such that
>> > vm.zone_reclaim_mode=0.
> The change will definitely spread allocations out to all nodes then
> and it's plausible that the remote references will hurt kernel object
> allocations in a tight loop. Just to confirm, could you rerun the
> test with zone_reclaim_mode enabled to make the allocator stay in the
> local zones?
Yeah, setting vm.zone_reclaim_mode=1 fixes it pretty instantaneously.
For what it's worth, I'm pretty convinced that the numbers folks put in
the SLIT tables are, at best, horribly inconsistent from system to
system. At worst, they're utter fabrications not linked at all to the
reality of the actual latencies.
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next prev parent reply other threads:[~2013-11-22 6:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-21 22:57 Dave Hansen
2013-11-22 5:22 ` Johannes Weiner
2013-11-22 6:18 ` Dave Hansen [this message]
2013-11-22 6:38 ` Johannes Weiner
2013-11-22 16:57 ` Dave Hansen
2013-11-26 10:32 ` Mel Gorman
2013-12-06 17:43 ` Dave Hansen
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