On 12/08/2018 16:34, Sad Clouds wrote:
OK, I cloned NetBSD VM, kept everything the same, but installed Debian with XFS file system. $ dd if=/dev/zero of=out bs=1M count=10000 conv=fsync this gives 682 MB/sec which is what I would normally expect
Just dug into my IO settings a bit.My NetBSD VM has 'Use Host IO cache' ticked and my ubuntu VM does not although I did rerun the test with the box unticked on NetBSD and got the same result. I am running all my virtual box tests on a Windows 10 host and nothing I can do is getting different performance results. I've always turned off the use host io cache setting as its always seemed silly to me to burn memory twice for disk IO caches.
So this is some sort of interaction between the way the NetBSD host does IO and the linux host OS that the linux VM's don't hit.
Mike