On Sat, Feb 27, 2010 at 06:36:37AM -0500, Justin Piszcz wrote: > Besides large sequential I/O, ext4 seems to be MUCH faster than XFS when > working with many small files. > > EXT4 > > p63:/r1# sync; /usr/bin/time bash -c 'tar xf linux-2.6.33.tar; sync' > 0.18user 2.43system 0:02.86elapsed 91%CPU (0avgtext+0avgdata 5216maxresident)k > 0inputs+0outputs (0major+971minor)pagefaults 0swaps > linux-2.6.33 linux-2.6.33.tar > p63:/r1# sync; /usr/bin/time bash -c 'rm -rf linux-2.6.33; sync' > 0.02user 0.98system 0:01.03elapsed 97%CPU (0avgtext+0avgdata 5216maxresident)k > 0inputs+0outputs (0major+865minor)pagefaults 0swaps > > XFS > > p63:/r1# sync; /usr/bin/time bash -c 'tar xf linux-2.6.33.tar; sync' > 0.20user 2.62system 1:03.90elapsed 4%CPU (0avgtext+0avgdata 5200maxresident)k > 0inputs+0outputs (0major+970minor)pagefaults 0swaps > p63:/r1# sync; /usr/bin/time bash -c 'rm -rf linux-2.6.33; sync' > 0.03user 2.02system 0:29.04elapsed 7%CPU (0avgtext+0avgdata 5200maxresident)k > 0inputs+0outputs (0major+864minor)pagefaults 0swaps Mount XFS with "-o logbsize=262144". Metadata intensive workloads on XFS are log IO bound, so larger log buffer size makes a big difference. On 2.6.33 kernels on a single 15krpm SCSI drive I've been getting ~21s for the untar, and 8s for the rm -rf with that option set. Still slower than ext4, but nowhere near as bad. > So I guess that's the tradeoff, for massive I/O you should use XFS, else, > use EXT4? I wouldn't consider writing an 11GB file "massive IO", nor would I consider an 600MB/s massive, either, since you can get that out of a sub-$10k server these days.... > I still would like to know however, why 350MiB/s seems to be the maximum > performance I can get from two different md raids (that easily do 600MiB/s > with XFS). Check whether the dd process on ext4 is CPU bound.... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- 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
