diff options
| author | Mel Gorman <mel@csn.ul.ie> | 2009-06-16 18:32:12 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-16 22:47:35 -0400 |
| commit | 418589663d6011de9006425b6c5721e1544fb47a (patch) | |
| tree | ef37fb026d3e38191d6b5c99bc95c190fa98d0fb /Documentation/vm/balance | |
| parent | a3af9c389a7f3e675313f442fdd8c247c1cdb66b (diff) | |
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 <mel@csn.ul.ie>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/vm/balance')
| -rw-r--r-- | Documentation/vm/balance | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/Documentation/vm/balance b/Documentation/vm/balance index bd3d31bc4915..c46e68cf9344 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 | |||
| 75 | alleviate memory pressure on any zone in the page's node that has fallen below | 75 | alleviate memory pressure on any zone in the page's node that has fallen below |
| 76 | its watermark. | 76 | its watermark. |
| 77 | 77 | ||
| 78 | pages_min/pages_low/pages_high/low_on_memory/zone_wake_kswapd: These are | 78 | watemark[WMARK_MIN/WMARK_LOW/WMARK_HIGH]/low_on_memory/zone_wake_kswapd: These |
| 79 | per-zone fields, used to determine when a zone needs to be balanced. When | 79 | are per-zone fields, used to determine when a zone needs to be balanced. When |
| 80 | the number of pages falls below pages_min, the hysteric field low_on_memory | 80 | the number of pages falls below watermark[WMARK_MIN], the hysteric field |
| 81 | gets set. This stays set till the number of free pages becomes pages_high. | 81 | low_on_memory gets set. This stays set till the number of free pages becomes |
| 82 | When low_on_memory is set, page allocation requests will try to free some | 82 | watermark[WMARK_HIGH]. When low_on_memory is set, page allocation requests will |
| 83 | pages in the zone (providing GFP_WAIT is set in the request). Orthogonal | 83 | try to free some pages in the zone (providing GFP_WAIT is set in the request). |
| 84 | to this, is the decision to poke kswapd to free some zone pages. That | 84 | Orthogonal to this, is the decision to poke kswapd to free some zone pages. |
| 85 | decision is not hysteresis based, and is done when the number of free | 85 | That decision is not hysteresis based, and is done when the number of free |
| 86 | pages is below pages_low; in which case zone_wake_kswapd is also set. | 86 | pages is below watermark[WMARK_LOW]; in which case zone_wake_kswapd is also set. |
| 87 | 87 | ||
| 88 | 88 | ||
| 89 | (Good) Ideas that I have heard: | 89 | (Good) Ideas that I have heard: |