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| author | Theodore Ts'o <tytso@mit.edu> | 2008-10-09 23:53:47 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-10-09 23:53:47 -0400 |
| commit | 240799cdf22bd789ea6852653c3b879d35ad0a6c (patch) | |
| tree | e696b60cc103f23838b5c14d8d397f692abffbc3 /Documentation | |
| parent | 37515facd001942221d68171c81c1f46d54ffdd0 (diff) | |
| download | op-kernel-dev-240799cdf22bd789ea6852653c3b879d35ad0a6c.zip op-kernel-dev-240799cdf22bd789ea6852653c3b879d35ad0a6c.tar.gz | |
ext4: Use readahead when reading an inode from the inode table
With modern hard drives, reading 64k takes roughly the same time as
reading a 4k block. So request readahead for adjacent inode table
blocks to reduce the time it takes when iterating over directories
(especially when doing this in htree sort order) in a cold cache case.
With this patch, the time it takes to run "git status" on a kernel
tree after flushing the caches via "echo 3 > /proc/sys/vm/drop_caches"
is reduced by 21%.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/filesystems/ext4.txt | 6 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 3 |
2 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt index 0d53949..2890579 100644 --- a/Documentation/filesystems/ext4.txt +++ b/Documentation/filesystems/ext4.txt @@ -177,6 +177,11 @@ barrier=<0|1(*)> This enables/disables the use of write barriers in your disks are battery-backed in one way or another, disabling barriers may safely improve performance. +inode_readahead=n This tuning parameter controls the maximum + number of inode table blocks that ext4's inode + table readahead algorithm will pre-read into + the buffer cache. The default value is 32 blocks. + orlov (*) This enables the new Orlov block allocator. It is enabled by default. @@ -252,6 +257,7 @@ stripe=n Number of filesystem blocks that mballoc will try delalloc (*) Deferring block allocation until write-out time. nodelalloc Disable delayed allocation. Blocks are allocation when data is copied from user to page cache. + Data Mode ========= There are 3 different data modes: diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index d9ac970..d831d24 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -956,6 +956,9 @@ Table 1-10: Files in /proc/fs/ext4/<devname> files are packed closely together. Each large file will have its blocks allocated out of its own unique preallocation pool. +inode_readahead Tuning parameter which controls the maximum number of + inode table blocks that ext4's inode table readahead + algorithm will pre-read into the buffer cache .............................................................................. |
