From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mel Gorman Message-Id: <20070410160244.10742.42187.sendpatchset@skynet.skynet.ie> Subject: [PATCH 0/4] Updates to groupings pages by mobility patches Date: Tue, 10 Apr 2007 17:02:44 +0100 (IST) Sender: owner-linux-mm@kvack.org Return-Path: To: akpm@linux-foundation.org Cc: Mel Gorman , linux-mm@kvack.org List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org