From 551883ae8c9c31460e796e7b1b8aa9069de268b4 Mon Sep 17 00:00:00 2001 From: Nishanth Aravamudan Date: Tue, 29 Apr 2008 00:58:26 -0700 Subject: [PATCH] page allocator: explicitly retry hugepage allocations Add __GFP_REPEAT to hugepage allocations. Do so to not necessitate userspace putting pressure on the VM by repeated echo's into /proc/sys/vm/nr_hugepages to grow the pool. With the previous patch to allow for large-order __GFP_REPEAT attempts to loop for a bit (as opposed to indefinitely), this increases the likelihood of getting hugepages when the system experiences (or recently experienced) load. Mel tested the patchset on an x86_32 laptop. With the patches, it was easier to use the proc interface to grow the hugepage pool. The following is the output of a script that grows the pool as much as possible running on 2.6.25-rc9. Allocating hugepages test ------------------------- Disabling OOM Killer for current test process Starting page count: 0 Attempt 1: 57 pages Progress made with 57 pages Attempt 2: 73 pages Progress made with 16 pages Attempt 3: 74 pages Progress made with 1 pages Attempt 4: 75 pages Progress made with 1 pages Attempt 5: 77 pages Progress made with 2 pages 77 pages was the most it allocated but it took 5 attempts from userspace to get it. With the 3 patches in this series applied, Allocating hugepages test ------------------------- Disabling OOM Killer for current test process Starting page count: 0 Attempt 1: 75 pages Progress made with 75 pages Attempt 2: 76 pages Progress made with 1 pages Attempt 3: 79 pages Progress made with 3 pages And 79 pages was the most it got. Your patches were able to allocate the bulk of possible pages on the first attempt. Signed-off-by: Nishanth Aravamudan Cc: Andy Whitcroft Tested-by: Mel Gorman Cc: Dave Hansen Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 2c37c67ed8c..bbf953eeb58 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -199,7 +199,8 @@ static struct page *alloc_fresh_huge_page_node(int nid) struct page *page; page = alloc_pages_node(nid, - htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE|__GFP_NOWARN, + htlb_alloc_mask|__GFP_COMP|__GFP_THISNODE| + __GFP_REPEAT|__GFP_NOWARN, HUGETLB_PAGE_ORDER); if (page) { if (arch_prepare_hugepage(page)) { @@ -294,7 +295,8 @@ static struct page *alloc_buddy_huge_page(struct vm_area_struct *vma, } spin_unlock(&hugetlb_lock); - page = alloc_pages(htlb_alloc_mask|__GFP_COMP|__GFP_NOWARN, + page = alloc_pages(htlb_alloc_mask|__GFP_COMP| + __GFP_REPEAT|__GFP_NOWARN, HUGETLB_PAGE_ORDER); spin_lock(&hugetlb_lock);