On my VirtualBox 6.1.6 guest running -current amd64 I get: $ time cat 80mb > /dev/null cat 80mb > /dev/null 0.00s user 0.02s system 98% cpu 0.021 total
I presume you used /dev/zero by mistake - it is usually just a source of zeros. But with it the result is similar: $ time cat 80mb > /dev/zero cat 80mb > /dev/zero 0.00s user 0.01s system 97% cpu 0.011 total The results are identical for virtual disks attached to SATA and SCSI controllers; the physical storage is an M.2 SATA disk drive. On Wed, 29 Apr 2020 at 07:19, Sad Clouds <[email protected]> wrote: > > On Wed, 29 Apr 2020 06:57:28 +0200 > Roland Illig <[email protected]> wrote: > > > How can I further research where this artificial delay comes from, and > > finally fix it? > > I've always experienced slow disk I/O with NetBSD on VirtualBox, even > with fast SSD disks. Not sure if this is a NetBSD bug, or some > interaction with VirtualBox layers. See this post: > > https://mail-index.netbsd.org/netbsd-users/2018/03/18/msg020524.html > > I believe there is DTrace for NetBSD, so if you have the time you can > profile kernel paths and see where the latency comes from. -- ----
