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Re: Slow I/O on NetBSD domU (on Debian dom0)

  NetBSD PV domUs, instead (tried with a freshly compiled netbsd-5),
  seem to suffer from some I/O performance issues. Every time I start an
  intensive I/O task (like "tar xjvf pkgsrc.tar.bz2"), the NetBSD domU
  starts to lag. ssh connections take ages to be accepted, and generally

How are your "xbd" instances backed on the dom0?

I use NetBSD as the dom0, with files as virtual disks, via vnconfig
using the normal scripts.  I find about a <10% penalty on dd from the
file compared to dd from the raw dom0 disk, and then another <10%
penalty from the file on dom0 to the rxbd on domU.  So things seem good.

Things to check:

  can you dd from the backing store for the xbd at a reasonable speed?

  can you dd from the dom0 rxbd at a reasonable speed?

  what does 'systat vmstat' on the domU show during the heavy IO?

  what does the Linux equivalent show on the dom0?

I read a paper or web page long ago that claimed NetBSD as dom0 was
particularly efficient, but I can't find a reference to it quickly.

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