On Nov 07, 2007 16:42 -0600, Eric Sandeen wrote: > I tried ext4 vs. xfs doing 4 parallel 2G IO writes in 1M units to 4 > different subdirectories of the root of the filesystem: > > http://people.redhat.com/esandeen/seekwatcher/ext4_4_threads.png > http://people.redhat.com/esandeen/seekwatcher/xfs_4_threads.png > http://people.redhat.com/esandeen/seekwatcher/ext4_xfs_4_threads.png > > and then read them back sequentially: > > http://people.redhat.com/esandeen/seekwatcher/ext4_4_threads_read.png > http://people.redhat.com/esandeen/seekwatcher/xfs_4_threads_read.png > http://people.redhat.com/esandeen/seekwatcher/ext4_xfs_4_read_threads.png > > At the end of the write, ext4 had on the order of 400 extents/file, xfs > had on the order of 30 extents/file. It's clear especially from the > read graph that ext4 is interleaving the 4 files, in about 5M chunks on > average. Throughput seems comparable between ext4 & xfs nonetheless. The question is what the "best" result is for this kind of workload? In HPC applications the common case is that you will also have the data files read back in parallel instead of serially. The test shows ext4 finishing marginally faster in the write case, and marginally slower in the read case. What happens if you have 4 parallel readers? Cheers, Andreas -- Andreas Dilger Sr. Software Engineer, Lustre Group Sun Microsystems of Canada, Inc. - 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
