Does iozone use mmap() for IO? Olga
On Tue, Mar 9, 2010 at 2:57 AM, Matt Cowger <mcow...@salesforce.com> wrote: > Hi Everyone, > > > > It looks like I’ve got something weird going with zfs performance on a > ramdisk….ZFS is performing not even a 3rd of what UFS is doing. > > > > Short version: > > > > Create 80+ GB ramdisk (ramdiskadm), system has 96GB, so we aren’t swapping > > Create zpool on it (zpool create ram….) > > Change zfs options to turn off checksumming (don’t want it or need it), > atime, compression, 4K block size (this is the applications native > blocksize) etc. > > Run a simple iozone benchmark (seq. write, seq. read, rndm write, rndm > read). > > > > Same deal for UFS, replacing the ZFS stuff with newfs stuff and mounting the > UFS forcedirectio (no point in using a buffer cache memory for something > that’s already in memory) > > > > Measure IOPs performance using iozone: > > > > iozone -e -i 0 -i 1 -i 2 -n 5120 -O -q 4k -r 4k -s 5g > > > > With the ZFS filesystem I get around: > > ZFS > (seq write) 42360 (seq read)31010 (random > read)20953 (random write)32525 > > Not SOO bad, but here’s UFS: > > UFS > (seq write )42853 (seq read) 100761 (random read) > 100471 (random write) 101141 > > > > For all tests besides the seq write, UFS utterly destroys ZFS. > > > > I’m curious if anyone has any clever ideas on why this huge disparity in > performance exists. At the end of the day, my application will run on > either filesystem, it just surprises me how much worse ZFS performs in this > (admittedly edge case) scenario. > > > > --M > > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > > -- , _ _ , { \/`o;====- Olga Kryzhanovska -====;o`\/ } .----'-/`-/ olga.kryzhanov...@gmail.com \-`\-'----. `'-..-| / Solaris/BSD//C/C++ programmer \ |-..-'` /\/\ /\/\ `--` `--` _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
