On Wed, 2 Oct 2013, Benjamin LaHaise wrote: > Date: Wed, 2 Oct 2013 11:31:01 -0400 > From: Benjamin LaHaise <bcrl@xxxxxxxxx> > To: Eric Sandeen <sandeen@xxxxxxxxxx> > Cc: Jan Kara <jack@xxxxxxx>, Theodore Ts'o <tytso@xxxxxxx>, > Andreas Dilger <adilger.kernel@xxxxxxxxx>, linux-ext4@xxxxxxxxxxxxxxx > Subject: Re: [PATCH] ext4: add noorlov parameter to avoid spreading of > directory inodes > > On Wed, Oct 02, 2013 at 10:02:12AM -0500, Eric Sandeen wrote: > > I'm right with you on thinking a mount option should be a last resort. > > > > One thing I'm curious about - what changed from ext3 to ext4? I thought > > both defaulted to orlov and the same type of allocation behavior, more > > or less. I guess one change is that the "oldalloc" mount > > option went away. > > > (if it does come back, it should probably mirror what we had before, > > which was "oldalloc" not "noorlov" right?) > > The behaviour I'm looking for is not exactly the same as the orlov > allocator or the old allocator, but something that packs files as > closely together as possible. Half of this can be achieved with > fallocate(), but reducing the spreading of directory inodes can only be > accomplished with changes to the filesystem itself. The only reason > we're using multiple subdirectories is because of contention issues with > i_mutex (our application has to either fsync() the directory or mount > with dirsync to maintain consistency) during file creation and unlink(). What is the frequency of unlink operation in comparison to file creation ? There is a possible issue with the global goal cursors s_mb_last_group and s_mb_last_start which might make your files increasingly scattered across the disk. I've attempted to address this problem with my patch ext4: Try to better reuse recently freed space What is the usual size of the files this application is creating ? Thanks! -Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
