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Date:      Fri, 30 Aug 1996 15:13:39 -0700 (PDT)
From:      "Craig Shaver" <craig@ProGroup.COM>
To:        scsi@FreeBSD.org
Subject:   Re: NCR0+IBM DORS-32160 WA0A 2 gigs HD - assertion "cp" failed
Message-ID:  <199608302213.PAA13655@seabass.progroup.com>
In-Reply-To: <199608302023.WAA07150@x14.mi.uni-koeln.de> from "Stefan Esser" at Aug 30, 96 10:23:15 pm

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> 
> 
> Craig Shaver writes:
>  > > 
>  > > 
>  > > Brian Wang writes:
>  > >  > Hi,
del ...
>  > I get the same problem with the tyan 825 and an atlas xp34300wide 4.3g drive.
> 
> Hmmm, an Atlas ???
> 
> I've tried with any number of tags (upto 32) and heavy load
> from many processes accessing the disk at a time, and never
> had a single such error (using a 2GB Atlas).
> 
I can try some experiments to load different numbers of tags and let you know
what happens over time.  I'll try 32 tags next.

> 
>  > I'm getting a tekram 875 and a seagate uw drive and will be building
>  > up a new system.  I will use 2.1.5R and the driver from the tekram site
>  > that supports the tekram 390F.  They have patch kits there too.  Are you
>  > going to use any of their stuff?  Are you going for just generic support
>  > of the 875?  Is there any differences with the various 875 implementations
>  > that might allow for optimizations?
> 
> The 875 allows for many optimizations, and I plan to have the
> driver take advantage of them. But it is a HUGE effort to do 
> it right. (And since I don't get paid for it, it would be a 
> total waste of time if I did NOT try to do it right ;-)
> 


Please do take your time, I  would rather have a driver that worked
well.



> I have received test results from somebody who did FreeBSD tests
> for Tekram, and who tested my new code which calculates the pre-
> scaler parameters for the Ultra-SCSI chips.
> 
> I asked him to post the results, since I consider them very 
> interesting, but he did not do so, and I won't unless I get his
> permission, since he sent them in private mail.
> 
> The Tekram driver comes out significantly slower than either 
> the FreeBSD NCR driver, or an AH2940UW, which give quite similar
> results. The NCR driver can easily be configured to use more or 
> less tags at run-time, and the results with 4, 8 and 16 tags 
> clearly show that 8 tags gives the optimum performance. (The 
> default of 4 tags does make the driver consume less memory, 
> since each tag (== outstanding command) needs some storage to 
> keep the commands parameters.
> 
> Anyway, if you got the Tekram driver, just do some Bonnie tests
> (or whatever your benchmark of choice is) and post the results.
> 


I have none and have not tried to do any.  I will try to find "Bonnie"
and run it when I have this setup.  (a month or two)


I also have available a LDP  UW scsi pci board based on the 875.  If you
need some testing help let me know.  So far I have the asus200 (810),
tyan (825), ldp (875), and the tekram (875) is on the way.



del ....
> 
> But under 2.1.5, there should be no disruption of service, as you 
> suffer from under 2.1R, because of driver improvements. So just
> give it a try ...


hmmmm...., I looked through the ncr.c code when I had another problem
with the wide drive target ids.  I originally set the drive to a
target over 7.  The boot barfed on it and could not recognize the
disk until I put it back down to a target under 8.  In the code I
noticed that a mask was used for the target that was 7 in some places and
15 in others.  Have you tested for targets greater than 7 on any
of the 825's or 875's that allow for a dual channel.

Just curious.

> 
> Regards, STefan
> 
> PS: If you are going to use the 53c875 under 2.1.5R, you'll need the
>     following patch to /sys/pci/ncr.c to correctly set the clock 
>     pre-scaler register:


Mucho gracias amigo!  Have a good vacation!

I'll wait to here from you sometime next week I guess ... :)





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