> A few weeks ago I posted a patch for discussion that allowed ext4 to run > without a journal. Since that time I've integrated the excellent > comments from Andreas and fixed several serious bugs. We're currently > running with this patch and generating some performance numbers against > both ext2 (with backported reservations code) and ext4 with and without > a journal. It just so happens that running without a journal is > slightly faster for most everything. > > We did > iozone -T -t 4 s 2g -r 256k -T -I -i0 -i1 -i2 > > which creates 4 threads, each of which create and do reads and writes on > a 2G file, with a buffer size of 256K, using O_DIRECT for all file opens > to bypass the page cache. Results: > > ext2 ext4, default ext4, no journal > initial writes 13.0 MB/s 15.4 MB/s 15.7 MB/s > rewrites 13.1 MB/s 15.6 MB/s 15.9 MB/s > reads 15.2 MB/s 16.9 MB/s 17.2 MB/s > re-reads 15.3 MB/s 16.9 MB/s 17.2 MB/s > random readers 5.6 MB/s 5.6 MB/s 5.7 MB/s > random writers 5.1 MB/s 5.3 MB/s 5.4 MB/s > > So it seems that, so far, this was a useful exercise. Interesting although I'm not that surprised because those tests seem to do a lot of data changes (which are never journaled in fact) and tiny amount of metadata changes. If you run some benchmark doing lots of directory operations, I guess the numbers would be considerably different. Maybe trying dbench (I know it's kind of stupid ;) or postmark will show the differences better. Honza -- Jan Kara <jack@xxxxxxx> SuSE CR Labs -- 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
