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From: Mel Gorman <mel@csn.ul.ie>
To: akpm@linux-foundation.org
Cc: Mel Gorman <mel@csn.ul.ie>, linux-mm@kvack.org
Subject: [PATCH 0/4] Updates to groupings pages by mobility patches
Date: Tue, 10 Apr 2007 17:02:44 +0100 (IST)	[thread overview]
Message-ID: <20070410160244.10742.42187.sendpatchset@skynet.skynet.ie> (raw)

Some concerns were raised about performance hotpoints related to
grouping pages by mobility and the fact it was a configurable option. The
following four patches aim to address some of those concerns. They show
small performance benefits on kernbench but the important patch deals with
disabling grouping pages by mobility when there is not enough memory for it
to work.  With these set of patches against 2.6.21-rc6-mm1, it's reasonable
to get rid of page grouping by mobility as a compile-time option.

Patch 1 is a minor correctness issue. A check is made for MIGRATE_RESERVE
	during boot time before any block has been marked. The patch removes
	the unnecessary check.

Patch 2 checks when the system does not have enough memory overall to make
	grouping pages by mobility useful. This patch disables page groupings
	when the situation occurs. This is important for low-memory machines.

Patch 3 is a performance improvement in the per-cpu allocator to do less work
	when grouping pages by mobility

Patch 4 is a performance improvement when looking up flags affecting a
	MAX_ORDER_NR_PAGES area in the SPARSEMEM case. There is no need to
	align the PFN to an area boundary.

The net effect of these patches is a small performance increase and that
I'd be happy to drop the configure option for grouping pages by mobility.
-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

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             reply	other threads:[~2007-04-10 16:02 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-10 16:02 Mel Gorman [this message]
2007-04-10 16:03 ` [PATCH 1/4] Remove unnecessary check for MIGRATE_RESERVE during boot Mel Gorman
2007-04-10 16:03 ` [PATCH 2/4] Do not group pages by mobility type on low memory systems Mel Gorman
2007-04-10 16:03 ` [PATCH 3/4] Reduce the amount of time spent in the per-cpu allocator Mel Gorman
2007-04-10 16:04 ` [PATCH 4/4] Do not block align PFN when looking up the pageblock PFN Mel Gorman

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