Re: [zfs-discuss] terrible ZFS performance compared to UFS on ramdisk (70% drop)

[Roch Bourbonnais]

will represent a significant drain of CPU resource.

-r


Le 8 mars 10 à 17:57, Matt Cowger a écrit :

I think This is highlighting that there is extra CPU requirement to manage small blocks in ZFS. The table would probably turn over if you go to 16K zfs records and 16K reads/writes form the application. Next step for you is to figure how much reads/writes IOPS do you expect to take in the real workloads and whether or not the filesystem portion

Hi Everyone,



Short version:


Create zpool on it (zpool create ram….)




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:

Not SOO bad, but here’s UFS:


For all tests besides the seq write, UFS utterly destroys ZFS.



--M
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

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. Create 80+ GB ramdisk (ramdiskadm), system has 96GB, so we aren’t swapping 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) ZFS (seq write) 42360 (seq read)31010 (random read)20953 (random write)32525 UFS (seq write )42853 (seq read) 100761 (random read) 100471 (random write) 101141 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.

smime.p7s
Description: S/MIME cryptographic signature

_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss