It can, but doesn't in the command line shown below. M
On Mar 8, 2010, at 6:04 PM, "ольга крыжановская" <olga.kryzh anov...@gmail.com> wrote: > 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 dispar >> ity 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
