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>
This commit is contained in:
Theodore Ts'o
2008-10-09 23:53:47 -04:00
parent 37515facd0
commit 240799cdf2
6 changed files with 100 additions and 71 deletions

View File

@@ -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
..............................................................................