On 22 March 2016 at 14:47, Thor Lancelot Simon <[email protected]> wrote: > The controller is a ciss. I observed the same problems with an arcmsr. > > I don't think this has anything to do with the controller. At 1/2 the > data and request rate, under Xen we use 60% CPU as interrupt time > while with a native kernel, it's 1-3%. > > The same test's easy to reproduce with any Xen dom0, since all you have > to do is dd from the raw disk into /dev/null. Do you see >40% interrupt > time and all your idle CPU go away? That's the issue.
In case it helps, with a recent netbsd-7 dom0 kernel I see - around 20% interrupt, 70% idle with dd if=/dev/wd1d of=/dev/null bs=64k - around 4% interrupt, 80% idle with dd if=/dev/rwd1d of=/dev/null bs=64k wd1 is an SSD, but I get ~ the same overhead with the spinning rust on wd0 System is a Dell Optiplex 990 SFF 3.4Ghz i7, xen4.5 I will note that I have found the machine laggy if I ran pkgsrc builds in dom0 Kernel is a generic plus npf - dmest at http://sync.absd.org/hermes.dmesg
