On 16 November 2010 13:15, Christer Solskogen <christer.solsko...@gmail.com> wrote: > On Tue, Nov 16, 2010 at 12:47 PM, Ivan Voras <ivo...@freebsd.org> wrote: > >> You can easily test it - use the stick as a simple disk device with UFS and >> see how much CPU does it take simply to talk to the device. > > See, that is why I think it is a ZFS issue. Because I did that. > I created a UFS filesystem on the same usb stick. Mounted it and did a > "dd if=/dev/zero of=/mnt/file". > The systemload goes +0.6 instead if +10.3. > > See: > CPU: 0.0% user, 0.0% nice, 0.6% system, 0.0% interrupt, 99.3% idle > Mem: 832M Active, 960M Inact, 7017M Wired, 2600K Cache, 1237M Buf, 3063M Free > Swap: 8192M Total, 8192M Free > > PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND > 38261 root 1 46 0 5776K 1112K wdrain 7 0:07 4.98% dd > > But when using it as cache device for zfs: > > CPU: 0.0% user, 0.0% nice, 11.9% system, 0.0% interrupt, 88.1% idle > Mem: 832M Active, 193M Inact, 5782M Wired, 2592K Cache, 1237M Buf, 5066M Free > Swap: 8192M Total, 8192M Free > > The funny thing is that when I add the device (and some cache is added > to it) the load is normal. But the load goes up when nothing is > written to it (or beeing read from it)
You mean you have system load on an otherwise idle system? Try this: 1) start "top" with parameters -H -S, see if anything is using the CPU time 2) start "gstat", see if anything is using IO, and if it's particularly slow or busying the device too much _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
