"High" cpu usage when using ZFS cache device
freebsd at jdc.parodius.com
Tue Nov 16 16:01:53 UTC 2010
On Tue, Nov 16, 2010 at 04:53:57PM +0100, Christer Solskogen wrote:
> On Tue, Nov 16, 2010 at 2:11 PM, Ollivier Robert
> <roberto at keltia.freenix.fr> wrote:
> > According to Christer Solskogen:
> >> 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.
> > Do not forget that everything that is read/written from/to USB devices goes through the CPU (no DMA or anything for USB devices).
> I didn't forget that. Thats why I also tested with UFS. And I do not
> have the same issue with that.
> With top -HS I discovered this:
> 5 root -8 - 0K 76K zio->i 4 403.2H 85.06%
Please provide the output from:
sysctl -a | grep vfs.zfs.arc
sysctl -a | grep vm.kmem
| Jeremy Chadwick jdc at parodius.com |
| Parodius Networking http://www.parodius.com/ |
| UNIX Systems Administrator Mountain View, CA, USA |
| Making life hard for others since 1977. PGP: 4BD6C0CB |
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