From 396faf0303d273219db5d7eb4a2879ad977ed185 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 17 Jul 2007 04:03:13 -0700 Subject: Allow huge page allocations to use GFP_HIGH_MOVABLE Huge pages are not movable so are not allocated from ZONE_MOVABLE. However, as ZONE_MOVABLE will always have pages that can be migrated or reclaimed, it can be used to satisfy hugepage allocations even when the system has been running a long time. This allows an administrator to resize the hugepage pool at runtime depending on the size of ZONE_MOVABLE. This patch adds a new sysctl called hugepages_treat_as_movable. When a non-zero value is written to it, future allocations for the huge page pool will use ZONE_MOVABLE. Despite huge pages being non-movable, we do not introduce additional external fragmentation of note as huge pages are always the largest contiguous block we care about. [akpm@linux-foundation.org: various fixes] Signed-off-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'kernel/sysctl.c') diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 2ce7acf841ae..48dae075d5c2 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -826,6 +826,14 @@ static ctl_table vm_table[] = { .mode = 0644, .proc_handler = &proc_dointvec, }, + { + .ctl_name = CTL_UNNUMBERED, + .procname = "hugepages_treat_as_movable", + .data = &hugepages_treat_as_movable, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &hugetlb_treat_movable_handler, + }, #endif { .ctl_name = VM_LOWMEM_RESERVE_RATIO, -- cgit v1.2.3