On Sun, Sep 25, 2011 at 12:16:12AM -0600, Andreas Dilger wrote: > > It would be possible to do something like this in the ext4 readdir > code to do dirent readahead, sort, and then prefetch the inodes > in order (partially or completely, depending on the directory size), > but as yet we aren't working on anything at the ext4 level. What we have in ext4 right now is if we need to do disk i/o to read from the inode table, we will read in adjacent blocks from the inode table, on the theory that the effort needed to read in 32k versus 4k is pretty much the same. So if the inodes were allocated all at the same time, they will be sequentially ordered, and so the inode table readahead should help quite a lot. I'll note that with really large maildirs, especially on a mail server with many other maildirs, over time the inodes for each individual file will get scattered all over the place, and so pretty much any scheme that uses a inode table separate from the blocks where the directory entries are stored is going to get hammered by this use case. Ultimately, the best way to solve this problem is a more intelligent application that caches the contents of the key headers in a database, so you don't need to scan the contents of the entire Maildir when doing common IMAP operations. - Ted _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
