From: Nick Piggin <npiggin@suse.de>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Lin Ming <ming.m.lin@intel.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
Linux Memory Management List <linux-mm@kvack.org>,
Rik van Riel <riel@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Christoph Lameter <cl@linux-foundation.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Zhang Yanmin <yanmin_zhang@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [RFC PATCH 00/19] Cleanup and optimise the page allocator V2
Date: Tue, 3 Mar 2009 10:04:42 +0100 [thread overview]
Message-ID: <20090303090442.GA17042@wotan.suse.de> (raw)
In-Reply-To: <20090303082511.GA2809@csn.ul.ie>
On Tue, Mar 03, 2009 at 08:25:12AM +0000, Mel Gorman wrote:
> On Tue, Mar 03, 2009 at 05:42:40AM +0100, Nick Piggin wrote:
> > or if some change resulted in more cross-cpu operations then it
> > could result in worse cache efficiency.
> >
>
> It occured to me before sleeping last night that there could be a lot
> of cross-cpu operations taking place in the buddy allocator itself. When
> bulk-freeing pages, we have to examine all the buddies and merge them. In
> the case of a freshly booted system, many of the pages of interest will be
> within the same MAX_ORDER blocks. If multiple CPUs bulk free their pages,
> they'll bounce the struct pages between each other a lot as we are writing
> those cache lines. However, this would be incurring with or without my patches.
Oh yes it would definitely be a factor I think.
> > OK, but the dynamic behaviour too. Free page A, free page B, allocate page
> > A allocate page B etc.
> >
> > The hot/cold removal would be an obvious example of what I mean, although
> > that wasn't included in this recent patchset anyway.
> >
>
> I get your point though, I'll keep it in mind. I've gone from plain
> "reduce the clock cycles" to "reduce the cache misses" as if OLTP is
> sensitive to this it has to be addressed as well.
OK cool. The patchset did look pretty good for reducing clock cycles
though, so hopefully it turns out to be something simple.
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next prev parent reply other threads:[~2009-03-03 9:04 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-24 12:16 [RFC PATCH 00/19] Cleanup and optimise the page allocator V2 Mel Gorman
2009-02-24 12:16 ` [PATCH 01/19] Replace __alloc_pages_internal() with __alloc_pages_nodemask() Mel Gorman
2009-02-24 12:16 ` [PATCH 02/19] Do not sanity check order in the fast path Mel Gorman
2009-02-24 12:16 ` [PATCH 03/19] Do not check NUMA node ID when the caller knows the node is valid Mel Gorman
2009-02-24 17:17 ` Christoph Lameter
2009-02-24 12:17 ` [PATCH 04/19] Convert gfp_zone() to use a table of precalculated values Mel Gorman
2009-02-24 16:43 ` Christoph Lameter
2009-02-24 17:07 ` Mel Gorman
2009-02-24 12:17 ` [PATCH 05/19] Re-sort GFP flags and fix whitespace alignment for easier reading Mel Gorman
2009-02-24 12:17 ` [PATCH 06/19] Check only once if the zonelist is suitable for the allocation Mel Gorman
2009-02-24 17:24 ` Christoph Lameter
2009-02-24 12:17 ` [PATCH 07/19] Break up the allocator entry point into fast and slow paths Mel Gorman
2009-02-24 12:17 ` [PATCH 08/19] Simplify the check on whether cpusets are a factor or not Mel Gorman
2009-02-24 17:27 ` Christoph Lameter
2009-02-24 17:55 ` Mel Gorman
2009-02-24 12:17 ` [PATCH 09/19] Move check for disabled anti-fragmentation out of fastpath Mel Gorman
2009-02-24 12:17 ` [PATCH 10/19] Calculate the preferred zone for allocation only once Mel Gorman
2009-02-24 17:31 ` Christoph Lameter
2009-02-24 17:53 ` Mel Gorman
2009-02-24 12:17 ` [PATCH 11/19] Calculate the migratetype " Mel Gorman
2009-02-24 12:17 ` [PATCH 12/19] Calculate the alloc_flags " Mel Gorman
2009-02-24 12:17 ` [PATCH 13/19] Inline __rmqueue_smallest() Mel Gorman
2009-02-24 12:17 ` [PATCH 14/19] Inline buffered_rmqueue() Mel Gorman
2009-02-24 12:17 ` [PATCH 15/19] Do not call get_pageblock_migratetype() more than necessary Mel Gorman
2009-02-24 12:17 ` [PATCH 16/19] Do not disable interrupts in free_page_mlock() Mel Gorman
2009-02-24 12:17 ` [PATCH 17/19] Do not setup zonelist cache when there is only one node Mel Gorman
2009-02-24 12:17 ` [PATCH 18/19] Do not check for compound pages during the page allocator sanity checks Mel Gorman
2009-02-24 12:17 ` [PATCH 19/19] Split per-cpu list into one-list-per-migrate-type Mel Gorman
2009-02-26 9:10 ` [RFC PATCH 00/19] Cleanup and optimise the page allocator V2 Lin Ming
2009-02-26 9:26 ` Pekka Enberg
2009-02-26 9:27 ` Lin Ming
2009-02-26 11:03 ` Mel Gorman
2009-02-26 11:18 ` Pekka Enberg
2009-02-26 11:22 ` Mel Gorman
2009-02-26 12:27 ` Lin Ming
2009-02-27 8:44 ` Lin Ming
2009-03-02 11:21 ` Mel Gorman
2009-03-02 11:39 ` Nick Piggin
2009-03-02 12:16 ` Mel Gorman
2009-03-03 4:42 ` Nick Piggin
2009-03-03 8:25 ` Mel Gorman
2009-03-03 9:04 ` Nick Piggin [this message]
2009-03-03 13:51 ` Mel Gorman
2009-03-03 16:31 ` Christoph Lameter
2009-03-03 21:48 ` Mel Gorman
2009-03-04 2:05 ` Zhang, Yanmin
2009-03-04 7:23 ` Peter Zijlstra
2009-03-04 8:31 ` Zhang, Yanmin
2009-03-04 9:07 ` Nick Piggin
2009-03-05 1:56 ` Zhang, Yanmin
2009-03-05 10:34 ` Ingo Molnar
2009-03-06 8:33 ` Lin Ming
2009-03-06 9:39 ` Ingo Molnar
2009-03-06 13:03 ` Mel Gorman
2009-03-09 1:50 ` Zhang, Yanmin
2009-03-09 7:31 ` Lin Ming
2009-03-09 7:03 ` Lin Ming
2009-03-04 18:04 ` Mel Gorman
2009-02-26 16:28 ` Christoph Lameter
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