linux-kernel - [PATCH 1/5] hugetlbfs: fix hugetlb_get_unmapped

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Date:	Fri, 13 Jan 2012 19:44:04 +0800
From:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	William Irwin <wli@...omorphy.com>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/5] hugetlbfs: fix hugetlb_get_unmapped_area

Using/updating cached_hole_size and free_area_cache properly to speedup
find free region

Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
---
 fs/hugetlbfs/inode.c |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index e425ad9..9e0794a 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -154,10 +154,12 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 			return addr;
 	}

-	start_addr = mm->free_area_cache;
-
-	if (len <= mm->cached_hole_size)
+	if (len > mm->cached_hole_size)
+		start_addr = mm->free_area_cache;
+	else {
 		start_addr = TASK_UNMAPPED_BASE;
+		mm->cached_hole_size = 0;
+	}

 full_search:
 	addr = ALIGN(start_addr, huge_page_size(h));
@@ -171,13 +173,18 @@ full_search:
 			 */
 			if (start_addr != TASK_UNMAPPED_BASE) {
 				start_addr = TASK_UNMAPPED_BASE;
+				mm->cached_hole_size = 0;
 				goto full_search;
 			}
 			return -ENOMEM;
 		}

-		if (!vma || addr + len <= vma->vm_start)
+		if (!vma || addr + len <= vma->vm_start) {
+			mm->free_area_cache = addr + len;
 			return addr;
+		}
+		if (addr + mm->cached_hole_size < vma->vm_start)
+			mm->cached_hole_size = vma->vm_start - addr;
 		addr = ALIGN(vma->vm_end, huge_page_size(h));
 	}
 }
-- 
1.7.7.5

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