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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