Hi Folks, I was wondering if anyone has an pointers/suggestions on how I might increase disk performance of a HVM zvol-backed DomU? - this is my first DomU, so hopefully its something obvious Running bonnie++ shows the DomU's performance to be 3 orders of magnitude worse than Dom0's, which itself is half as good as when not running xVM at all (see bottom for bonnie++ results) I'm using a 2*raidz2 SAN for the DomU backing. I'm also using a separate disk (a compact flash) for a ZFS-based root disk. The system has a single quad-core opteron with 8G phyical memory, but when I boot Dom0, I pass "dom0_mem=4G dom0_max_vcpus=2 dom0_vcpus_pin=true" on the "kernel$" line to limit how much mem/cpu the Dom0 can use. When I created my DomU, I first created the zvol: zfs create -V 4G tank/puffy-root-disk and then installed the OS with something like this: virt-install --name puffy --hvm --ram 512 --vnc \ --file /dev/zvol/dsk/tank/puffy-root-disk \ --cdrom /tank/install43_amd64.iso --noautoconsole \ --os-type=unix --os-variant=openbsd4 --vcpus=1 BTW, I really didn't have to run bonnie++ to know the performance wasn't good since: 1) the install took ~40 minutes (normally ~2 minutes) 2) `xm top` showed the DomU as "blocked" almost the whole time I really haven't found much info on ways to improve this, does anyone have any pointers? PS: bonnie++ output below! Thanks, KentBonnie++ on plain system (not Dom0) Version 1.03d ------ Sequential Output ------ --- Sequential Input --- --Random- -Per Char- --Block-- -Rewrite- --Per Char-- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP san 16G 74241 93 304695 80 199290 57 74182 99 601348 69 1812 5 ------ Sequential Create ------ -------- Random Create -------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP 16 23050 99 +++++ +++ +++++ +++ 22865 99 +++++ +++ 32317 92 Bonnie++ on Dom0 Version 1.03d ------ Sequential Output ------ --- Sequential Input --- --Random- -Per Char- --Block-- -Rewrite- --Per Char-- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP san 8G 67051 85 166574 59 126454 63 71058 96 362940 76 1645 11 ------ Sequential Create ------ -------- Random Create -------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP 16 15815 99 +++++ +++ 22903 99 15222 99 +++++ +++ 22339 99 Bonnie++ in zvol-backed DomU (openbsd 4.3, hvm) Version 1.03 ------ Sequential Output ------ --- Sequential Input --- --Random- -Per Char- --Block-- -Rewrite- --Per Char-- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP puffy 300M 451 0 295 0 184 0 976 4 1521 2 26.8 1 ------ Sequential Create ------ -------- Random Create -------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP 16 8 1 +++++ +++ 16 1 8 1 +++++ +++ 10 0 |
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