On Wed, 29 Apr 2020 15:55:31 +0100 Mike Pumford <[email protected]> wrote:
> I haven't tried with anything later than 7 but I use virtual box > hosted on windows a lot with ahci storage emulation. In the last > tests I did I was getting 100MB/s write performance with both Ubuntu > (kernel 4.4) and NetBSD 7. For reference the underlying disk in that > case was a 2TB ATA attached to an AHCI controller. What I notice when writing data to disk, with Linux VM there is very little CPU usage on the physical host, but with NetBSD (and other BSDs I guess) CPU usage shoots up. So Linux definitely has some optimizations. Not sure if this is down to Oracle guest additions, or Linux KVM acceleration. Or maybe it's NetBSD FFS, I got much better throughput with NetBSD + ZFS but that used 4 striped virtual disks. Tests below used 1 MiB block size, writing non-compressible data to the same 2TB SATA disk. Linux physical host running VirtualBox: Total 5.00 GiB: 36832.69 msec, 139.01 MiBs, 139.01 Ops Linux VM with XFS: Total 5.00 GiB: 60461.32 msec, 84.68 MiBs, 84.68 Ops NetBSD-9 VM FFS with logging: Total 5.00 GiB: 138410.84 msec, 36.99 MiBs, 36.99 Ops
