From: Mel Gorman <mel@csn.ul.ie>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Christoph Lameter <cl@linux-foundation.org>,
Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>,
David Rientjes <rientjes@google.com>,
Rik van Riel <riel@redhat.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 06/11] Export fragmentation index via /proc/extfrag_index
Date: Wed, 17 Mar 2010 11:33:26 +0000 [thread overview]
Message-ID: <20100317113326.GD12388@csn.ul.ie> (raw)
In-Reply-To: <20100317114321.4C9A.A69D9226@jp.fujitsu.com>
On Wed, Mar 17, 2010 at 11:49:49AM +0900, KOSAKI Motohiro wrote:
> > +/*
> > + * A fragmentation index only makes sense if an allocation of a requested
> > + * size would fail. If that is true, the fragmentation index indicates
> > + * whether external fragmentation or a lack of memory was the problem.
> > + * The value can be used to determine if page reclaim or compaction
> > + * should be used
> > + */
> > +int fragmentation_index(unsigned int order, struct contig_page_info *info)
> > +{
> > + unsigned long requested = 1UL << order;
> > +
> > + if (!info->free_blocks_total)
> > + return 0;
> > +
> > + /* Fragmentation index only makes sense when a request would fail */
> > + if (info->free_blocks_suitable)
> > + return -1000;
> > +
> > + /*
> > + * Index is between 0 and 1 so return within 3 decimal places
> > + *
> > + * 0 => allocation would fail due to lack of memory
> > + * 1 => allocation would fail due to fragmentation
> > + */
> > + return 1000 - ( (1000+(info->free_pages * 1000 / requested)) / info->free_blocks_total);
> > +}
>
> Dumb question.
>
> your paper (http://portal.acm.org/citation.cfm?id=1375634.1375641) says
>
> fragmentation_index = 1 - (TotalFree/SizeRequested)/BlocksFree
>
> but your code have extra '1000+'. Why?
To get an approximation to three decimal places.
>
> Probably, I haven't understand the intention of this calculation.
>
>
>
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
next prev parent reply other threads:[~2010-03-17 11:33 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-12 16:41 [PATCH 0/11] Memory Compaction v4 Mel Gorman
2010-03-12 16:41 ` [PATCH 01/11] mm,migration: Take a reference to the anon_vma before migrating Mel Gorman
2010-03-14 15:01 ` Minchan Kim
2010-03-15 5:06 ` KAMEZAWA Hiroyuki
2010-03-17 1:44 ` KOSAKI Motohiro
2010-03-17 11:45 ` Mel Gorman
2010-03-17 16:38 ` Christoph Lameter
2010-03-18 11:12 ` Mel Gorman
2010-03-18 16:31 ` Christoph Lameter
2010-03-12 16:41 ` [PATCH 02/11] mm,migration: Do not try to migrate unmapped anonymous pages Mel Gorman
2010-03-15 0:28 ` Minchan Kim
2010-03-15 5:34 ` KAMEZAWA Hiroyuki
2010-03-15 6:28 ` Minchan Kim
2010-03-15 6:44 ` KAMEZAWA Hiroyuki
2010-03-15 7:09 ` KAMEZAWA Hiroyuki
2010-03-15 13:48 ` Minchan Kim
2010-03-15 7:11 ` Minchan Kim
2010-03-15 11:28 ` Mel Gorman
2010-03-15 12:48 ` Minchan Kim
2010-03-15 14:21 ` Mel Gorman
2010-03-15 14:33 ` Minchan Kim
2010-03-15 23:49 ` KAMEZAWA Hiroyuki
2010-03-17 2:12 ` KAMEZAWA Hiroyuki
2010-03-17 3:00 ` Minchan Kim
2010-03-17 3:15 ` KAMEZAWA Hiroyuki
2010-03-17 4:15 ` Minchan Kim
2010-03-17 4:19 ` KAMEZAWA Hiroyuki
2010-03-17 16:41 ` Christoph Lameter
2010-03-18 0:30 ` KAMEZAWA Hiroyuki
2010-03-17 12:07 ` Mel Gorman
2010-03-17 2:03 ` KOSAKI Motohiro
2010-03-17 11:51 ` Mel Gorman
2010-03-18 0:48 ` KOSAKI Motohiro
2010-03-18 11:14 ` Mel Gorman
2010-03-19 6:21 ` KOSAKI Motohiro
2010-03-19 8:59 ` Mel Gorman
2010-03-25 2:49 ` KOSAKI Motohiro
2010-03-25 8:32 ` Mel Gorman
2010-03-25 8:56 ` KOSAKI Motohiro
2010-03-25 9:18 ` Mel Gorman
2010-03-25 9:02 ` KAMEZAWA Hiroyuki
2010-03-25 9:09 ` KOSAKI Motohiro
2010-03-25 9:08 ` KAMEZAWA Hiroyuki
2010-03-25 9:21 ` Mel Gorman
2010-03-25 9:41 ` KAMEZAWA Hiroyuki
2010-03-25 9:59 ` KOSAKI Motohiro
2010-03-25 10:12 ` KAMEZAWA Hiroyuki
2010-03-25 13:39 ` Mel Gorman
2010-03-26 3:07 ` KOSAKI Motohiro
2010-03-26 13:49 ` Mel Gorman
2010-03-25 15:29 ` Minchan Kim
2010-03-26 0:58 ` KAMEZAWA Hiroyuki
2010-03-26 1:39 ` Minchan Kim
2010-03-25 14:35 ` Christoph Lameter
2010-03-25 16:16 ` Minchan Kim
2010-03-12 16:41 ` [PATCH 03/11] mm: Share the anon_vma ref counts between KSM and page migration Mel Gorman
2010-03-12 17:14 ` Rik van Riel
2010-03-15 5:35 ` KAMEZAWA Hiroyuki
2010-03-17 2:06 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 04/11] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA or memory hot-remove Mel Gorman
2010-03-17 2:28 ` KOSAKI Motohiro
2010-03-17 11:32 ` Mel Gorman
2010-03-17 16:37 ` Christoph Lameter
2010-03-17 23:56 ` KOSAKI Motohiro
2010-03-18 11:24 ` Mel Gorman
2010-03-19 6:21 ` KOSAKI Motohiro
2010-03-19 10:16 ` Mel Gorman
2010-03-25 3:28 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 05/11] Export unusable free space index via /proc/unusable_index Mel Gorman
2010-03-15 5:41 ` KAMEZAWA Hiroyuki
2010-03-15 9:48 ` Mel Gorman
2010-03-17 2:42 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 06/11] Export fragmentation index via /proc/extfrag_index Mel Gorman
2010-03-17 2:49 ` KOSAKI Motohiro
2010-03-17 11:33 ` Mel Gorman [this message]
2010-03-23 0:22 ` KOSAKI Motohiro
2010-03-23 12:03 ` Mel Gorman
2010-03-25 2:47 ` KOSAKI Motohiro
2010-03-25 8:47 ` Mel Gorman
2010-03-25 11:20 ` KOSAKI Motohiro
2010-03-25 14:11 ` Mel Gorman
2010-03-26 3:10 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 07/11] Memory compaction core Mel Gorman
2010-03-15 13:44 ` Minchan Kim
2010-03-15 14:41 ` Mel Gorman
2010-03-17 10:31 ` KOSAKI Motohiro
2010-03-17 11:40 ` Mel Gorman
2010-03-18 2:35 ` KOSAKI Motohiro
2010-03-18 11:43 ` Mel Gorman
2010-03-19 6:21 ` KOSAKI Motohiro
2010-03-18 17:08 ` Mel Gorman
2010-03-12 16:41 ` [PATCH 08/11] Add /proc trigger for memory compaction Mel Gorman
2010-03-17 3:18 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 09/11] Add /sys trigger for per-node " Mel Gorman
2010-03-17 3:18 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 10/11] Direct compact when a high-order allocation fails Mel Gorman
2010-03-16 2:47 ` Minchan Kim
2010-03-19 6:21 ` KOSAKI Motohiro
2010-03-19 6:31 ` KOSAKI Motohiro
2010-03-19 10:10 ` Mel Gorman
2010-03-25 11:22 ` KOSAKI Motohiro
2010-03-19 10:09 ` Mel Gorman
2010-03-25 11:08 ` KOSAKI Motohiro
2010-03-25 15:11 ` Mel Gorman
2010-03-26 6:01 ` KOSAKI Motohiro
2010-03-12 16:41 ` [PATCH 11/11] Do not compact within a preferred zone after a compaction failure Mel Gorman
2010-03-23 12:25 [PATCH 0/11] Memory Compaction v5 Mel Gorman
2010-03-23 12:25 ` [PATCH 06/11] Export fragmentation index via /proc/extfrag_index Mel Gorman
2010-03-23 17:37 ` Christoph Lameter
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