MSCP SCSI controller speed

[9000 VAX]

On 11/9/05, 9000 VAX <vax9000 at gmail.com> wrote:
> On 11/9/05, 9000 VAX <vax9000 at gmail.com> wrote:
> > >
> > >         dd if=syssrc.tar of=/dev/null bs=16k count=1000
> > 16384000 bytes transferred in 21 secs (780190 bytes/sec)
> > >         dd if=/dev/zero of=blah.null bs=16k count=1000
> > 16384000 bytes transferred in 35 secs (468114 bytes/sec)
> > >
> > > I suspect the write will be faster, and reflect the true speed of the i/o.
> > It is the opposite. strange.
>
> OK, maybe you are right. The write operation should be faster. The OS
> latency there is smaller. It was my controller that slowed down the
> write operation. I need to take a look to find out why.

The read operation used block mode DMA and the write operation used
burst mode DMA (slower). It seems there is more debugging work to do.

vax, 9000

>
> vax, 9000
>