Re: 4BSD process starvation during I/O

On Thu, Nov 24, 2005 at 07:52:30AM +0800, David Xu wrote:
> Kris Kennaway wrote:
> 
> >Perhaps this can be tweaked.
> >
> >Kris
> >
> >P.S. Please, no responses about how maybe someone could write a new
> >scheduler that doesn't have this property.
> >
> >
> > 
> >
> Can you try it again with FULL_PREEMPTION is turned on ?

Didn't really make a difference:

# sh dd.sh 1
mdconfig: ioctl(/dev/mdctl): No such file or directory
md0
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.325922 secs (202451919 bytes/sec)
# sh dd.sh 2
md0
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.828649 secs (146794428 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.828715 secs (146789108 bytes/sec)
# sh dd.sh 3
md0
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.875729 secs (143109929 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.879152 secs (142849247 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.883898 secs (142489377 bytes/sec)
# sh dd.sh 4
md0
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.834240 secs (146346968 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.858093 secs (144468255 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.894780 secs (141671047 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 3.108751 secs (86348335 bytes/sec)
# sh dd.sh 12
md0
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.860367 secs (144291681 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.885677 secs (142354961 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 1.983243 secs (135351757 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 3.409261 secs (78737139 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 3.762066 secs (71353204 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 3.910402 secs (68646510 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 5.086984 secs (52769079 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 5.566311 secs (48225018 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 5.816347 secs (46151897 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 6.818567 secs (39368309 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 7.375191 secs (36397085 bytes/sec)
16384+0 records in
16384+0 records out
268435456 bytes transferred in 7.568077 secs (35469440 bytes/sec)
#