From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon, 12 Jan 1998 13:58:43 -0600
From: G. David Butler gdb@dbSystems.com
Subject: [9fans] DPT PM2041W observations
Topicbox-Message-UUID: 6fce26e8-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19980112195843.tVkRS5jUDDmzmwTbj5h4GgHfziQ5pOCxAiRPEkc49sU@z>

>If the answer to that is "yes, with Tag Queueing", then I
>need some kind soul to help me get that to happen on the
>DPT adapter.  (The 154x can't do that.)  None of the
>documentation or source I have enable that feature.

I found and read the relevant parts of the SCSI-2 spec.
I now have tag queueing working.  I also found the DPO flag
which helps both cards.  Now the 154x does 1460MB/s (2% isn't
much, but anything helps.)

With tag queueing and 4 outstanding commands the DPT now gets
1370MB/s up from 1260MB/s.  At 8 outstanding commands it only
gets 1310MB/s.  At 2 outstanding commands it gets 1430MB/s.

So why does this 4th generation card with tag queueing support
run slower than the 1st generation design that is over 10 years
old?

David Butler
gdb@dbSystems.com