From 418589663d6011de9006425b6c5721e1544fb47a Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 16 Jun 2009 15:32:12 -0700 Subject: page allocator: use allocation flags as an index to the zone watermark ALLOC_WMARK_MIN, ALLOC_WMARK_LOW and ALLOC_WMARK_HIGH determin whether pages_min, pages_low or pages_high is used as the zone watermark when allocating the pages. Two branches in the allocator hotpath determine which watermark to use. This patch uses the flags as an array index into a watermark array that is indexed with WMARK_* defines accessed via helpers. All call sites that use zone->pages_* are updated to use the helpers for accessing the values and the array offsets for setting. Signed-off-by: Mel Gorman Reviewed-by: Christoph Lameter Cc: KOSAKI Motohiro Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Nick Piggin Cc: Dave Hansen Cc: Lee Schermerhorn Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/vm/balance | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'Documentation/vm') diff --git a/Documentation/vm/balance b/Documentation/vm/balance index bd3d31bc491..c46e68cf934 100644 --- a/Documentation/vm/balance +++ b/Documentation/vm/balance @@ -75,15 +75,15 @@ Page stealing from process memory and shm is done if stealing the page would alleviate memory pressure on any zone in the page's node that has fallen below its watermark. -pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are -per-zone fields, used to determine when a zone needs to be balanced. When -the number of pages falls below pages_min, the hysteric field low_on_memory -gets set. This stays set till the number of free pages becomes pages_high. -When low_on_memory is set, page allocation requests will try to free some -pages in the zone (providing GFP_WAIT is set in the request). Orthogonal -to this, is the decision to poke kswapd to free some zone pages. That -decision is not hysteresis based, and is done when the number of free -pages is below pages_low; in which case zone_wake_kswapd is also set. +watemark[WMARK_MIN/WMARK_LOW/WMARK_HIGH]/low_on_memory/zone_wake_kswapd: These +are per-zone fields, used to determine when a zone needs to be balanced. When +the number of pages falls below watermark[WMARK_MIN], the hysteric field +low_on_memory gets set. This stays set till the number of free pages becomes +watermark[WMARK_HIGH]. When low_on_memory is set, page allocation requests will +try to free some pages in the zone (providing GFP_WAIT is set in the request). +Orthogonal to this, is the decision to poke kswapd to free some zone pages. +That decision is not hysteresis based, and is done when the number of free +pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set. (Good) Ideas that I have heard: -- cgit v1.2.3-70-g09d2