Could you retest it with mmap() used? Olga
2010/3/9 Matt Cowger <mcow...@salesforce.com>: > 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 \ |-..-'` >> /\/\ /\/\ >> `--` `--` > -- , _ _ , { \/`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
