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authorAlex Tomas <alex@clusterfs.com>2008-01-29 00:19:52 -0500
committerTheodore Ts'o <tytso@mit.edu>2008-01-29 00:19:52 -0500
commitc9de560ded61faa5b754137b7753da252391c55a (patch)
tree2c4311377c4aa72450e27f531e198fe3e1c67db0 /Documentation/filesystems
parent1988b51e476bd097d910c9245b53f2e38aedaf0d (diff)
ext4: Add multi block allocator for ext4
Signed-off-by: Alex Tomas <alex@clusterfs.com> Signed-off-by: Andreas Dilger <adilger@clusterfs.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Eric Sandeen <sandeen@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/ext4.txt10
-rw-r--r--Documentation/filesystems/proc.txt39
2 files changed, 48 insertions, 1 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 4f329afe20e..560f88dc709 100644
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -86,9 +86,11 @@ Alex is working on a new set of patches right now.
When mounting an ext4 filesystem, the following option are accepted:
(*) == default
-extents ext4 will use extents to address file data. The
+extents (*) ext4 will use extents to address file data. The
file system will no longer be mountable by ext3.
+noextents ext4 will not use extents for newly created files
+
journal_checksum Enable checksumming of the journal transactions.
This will allow the recovery code in e2fsck and the
kernel to detect corruption in the kernel. It is a
@@ -206,6 +208,12 @@ nobh (a) cache disk block mapping information
"nobh" option tries to avoid associating buffer
heads (supported only for "writeback" mode).
+mballoc (*) Use the multiple block allocator for block allocation
+nomballoc disabled multiple block allocator for block allocation.
+stripe=n Number of filesystem blocks that mballoc will try
+ to use for allocation size and alignment. For RAID5/6
+ systems this should be the number of data
+ disks * RAID chunk size in file system blocks.
Data Mode
---------
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index dec99455321..4413a2d4646 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -857,6 +857,45 @@ CPUs.
The "procs_blocked" line gives the number of processes currently blocked,
waiting for I/O to complete.
+1.9 Ext4 file system parameters
+------------------------------
+Ext4 file system have one directory per partition under /proc/fs/ext4/
+# ls /proc/fs/ext4/hdc/
+group_prealloc max_to_scan mb_groups mb_history min_to_scan order2_req
+stats stream_req
+
+mb_groups:
+This file gives the details of mutiblock allocator buddy cache of free blocks
+
+mb_history:
+Multiblock allocation history.
+
+stats:
+This file indicate whether the multiblock allocator should start collecting
+statistics. The statistics are shown during unmount
+
+group_prealloc:
+The multiblock allocator normalize the block allocation request to
+group_prealloc filesystem blocks if we don't have strip value set.
+The stripe value can be specified at mount time or during mke2fs.
+
+max_to_scan:
+How long multiblock allocator can look for a best extent (in found extents)
+
+min_to_scan:
+How long multiblock allocator must look for a best extent
+
+order2_req:
+Multiblock allocator use 2^N search using buddies only for requests greater
+than or equal to order2_req. The request size is specfied in file system
+blocks. A value of 2 indicate only if the requests are greater than or equal
+to 4 blocks.
+
+stream_req:
+Files smaller than stream_req are served by the stream allocator, whose
+purpose is to pack requests as close each to other as possible to
+produce smooth I/O traffic. Avalue of 16 indicate that file smaller than 16
+filesystem block size will use group based preallocation.
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