On Sun, Oct 10, 2010 at 11:17:37PM +0400, Dmitry-T wrote: > My test OpenBSD: > > load from livecd bsdanywhere46-amd64 > > in different consoles: > > dd if=/dev/wd0c of=/dev/null bs=1m > dd if=/dev/wd0c of=/dev/null bs=1m > dd if=/dev/wd0c of=/dev/null bs=1m > iostat > top > > run: > dd if=/dev/urandom of=/dev/null > and disk read speed jump from 22Mb/s to 0.9Mb/s! > > renice 20 for last dd - throughput not change! > renice -20 for first three dd - throughput not change! > For check renice, run renice -20 for last dd - OpenBSD froze, even mouse. > > It is not secure. One script or program may load CPU and > database or another servers lost speed in disk operations. > > In Linux (test on 2.6.35 libre) renice work correct... > Why renice not work in OpenBSD? >
This is not how scheduling priorities work. You try to renice I/O bound processes. The scheduler priority only matters when processes are CPU bound. I also don't get it why people always use /dev/*random as input source for tests -- random numbers are not for free. -- :wq Claudio
