diff options
| author | Joonsoo Kim <[email protected]> | 2018-04-10 16:30:11 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2018-04-11 10:28:32 -0700 |
| commit | d3cda2337bbc9edd2a26b83cb00eaa8c048ff274 (patch) | |
| tree | 96e2745e71e23f92a7ce96b6a6b1eec3b69cd779 /Documentation/sysctl | |
| parent | 94723aafb9e76414fada7c1c198733a86f01ea8f (diff) | |
mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request
Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that
important to reserve. When ZONE_MOVABLE is used, this problem would
theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE
allocation request which is mainly used for page cache and anon page
allocation. So, fix it by setting 0 to
sysctl_lowmem_reserve_ratio[ZONE_HIGHMEM].
And, defining sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES - 1 size
makes code complex. For example, if there is highmem system, following
reserve ratio is activated for *NORMAL ZONE* which would be easyily
misleading people.
#ifdef CONFIG_HIGHMEM
32
#endif
This patch also fixes this situation by defining
sysctl_lowmem_reserve_ratio array by MAX_NR_ZONES and place "#ifdef" to
right place.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Joonsoo Kim <[email protected]>
Reviewed-by: Aneesh Kumar K.V <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Tested-by: Tony Lindgren <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: "Aneesh Kumar K . V" <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Laura Abbott <[email protected]>
Cc: Marek Szyprowski <[email protected]>
Cc: Michal Nazarewicz <[email protected]>
Cc: Russell King <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Diffstat (limited to 'Documentation/sysctl')
| -rw-r--r-- | Documentation/sysctl/vm.txt | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index ff234d229cbb..17256f2ad919 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -312,8 +312,6 @@ The lowmem_reserve_ratio is an array. You can see them by reading this file. % cat /proc/sys/vm/lowmem_reserve_ratio 256 256 32 - -Note: # of this elements is one fewer than number of zones. Because the highest - zone's value is not necessary for following calculation. But, these values are not used directly. The kernel calculates # of protection pages for each zones from them. These are shown as array of protection pages @@ -364,7 +362,8 @@ As above expression, they are reciprocal number of ratio. pages of higher zones on the node. If you would like to protect more pages, smaller values are effective. -The minimum value is 1 (1/1 -> 100%). +The minimum value is 1 (1/1 -> 100%). The value less than 1 completely +disables protection of the pages. ============================================================== |