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: Fri, 22 Nov 2013 08:57:06 -0800 [thread overview]
Message-ID: <528F8CE2.1000001@intel.com> (raw)
In-Reply-To: <20131122063845.GM3556@cmpxchg.org>
On 11/21/2013 10:38 PM, Johannes Weiner wrote:
> On Thu, Nov 21, 2013 at 10:18:44PM -0800, Dave Hansen wrote:
>> 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.
>
> You mean the reported distances should probably be bigger on this
> particular machine?
Yeah, or smaller on the others that made us switch zone_reclaim_mode at
the place where we do.
> But even when correct, zone_reclaim_mode might not be the best
> predictor. Just because it's not worth yet to invest direct reclaim
> efforts to stay local does not mean that remote references are free.
>
> I'm currently running some tests with the below draft to see if this
> would still leave us with enough fairness. Does the patch restore
> performance even with zone_reclaim_mode disabled?
Yeah, that at least works for the one test where it's been causing the
most trouble.
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next prev parent reply other threads:[~2013-11-22 16:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-21 22:57 NUMA? bisected performance regression 3.11->3.12 Dave Hansen
2013-11-22 5:22 ` Johannes Weiner
2013-11-22 6:18 ` Dave Hansen
2013-11-22 6:38 ` Johannes Weiner
2013-11-22 16:57 ` Dave Hansen [this message]
2013-11-26 10:32 ` Mel Gorman
2013-12-06 17:43 ` Dave Hansen
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