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authorMark Fasheh <mfasheh@suse.com>2010-04-05 18:17:15 -0700
committerJoel Becker <joel.becker@oracle.com>2010-05-05 18:18:07 -0700
commitb07f8f24dfe54da0f074b78949044842e8df881f (patch)
tree8cc24b0a1e02a9b7f1241fbfecca50ac6881b938 /Documentation/filesystems/ocfs2.txt
parent6b82021b9e91cd689fdffadbcdb9a42597bbe764 (diff)
ocfs2: change default reservation window sizes
The default reservation size of 4 (32-bit windows) is a bit too ambitious. Scale it back to 16 bits (resv_level=2). I have been testing various sizes on a 4-node cluster which runs a mixed workload that is heavily threaded. With a 256MB local alloc, I get *roughly* the following levels of average file fragmentation: resv_level=0 70% resv_level=1 21% resv_level=2 23% resv_level=3 24% resv_level=4 60% resv_level=5 did not test resv_level=6 60% resv_level=2 seemed like a good compromise between not letting windows be too small, but not so big that heavier workloads will immediately suffer without tuning. This patch also change the behavior of directory reservations - they now track file reservations. The previous compromise of giving directory windows only 8 bits wound up fragmenting more at some window sizes because file allocations had smaller unused windows to poach from. Signed-off-by: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Joel Becker <joel.becker@oracle.com>
Diffstat (limited to 'Documentation/filesystems/ocfs2.txt')
-rw-r--r--Documentation/filesystems/ocfs2.txt2
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/filesystems/ocfs2.txt b/Documentation/filesystems/ocfs2.txt
index 412df909593..32339e584a9 100644
--- a/Documentation/filesystems/ocfs2.txt
+++ b/Documentation/filesystems/ocfs2.txt
@@ -80,6 +80,6 @@ user_xattr (*) Enables Extended User Attributes.
nouser_xattr Disables Extended User Attributes.
acl Enables POSIX Access Control Lists support.
noacl (*) Disables POSIX Access Control Lists support.
-resv_level=4 (*) Set how agressive allocation reservations will be.
+resv_level=2 (*) Set how agressive allocation reservations will be.
Valid values are between 0 (reservations off) to 8
(maximum space for reservations).