rec.autos.simulators

PCI streaming/latency, Verite 3D accelerators and HX/VX

John Simmo

PCI streaming/latency, Verite 3D accelerators and HX/VX

by John Simmo » Fri, 07 Feb 1997 04:00:00



If your name is Perry, you can talk while the computer is working,
thus the term "Perry Concurrency".

Sam Gratri

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Sam Gratri » Sat, 08 Feb 1997 04:00:00



> > PCI Latency is on the individual card, in that cards PCI configuration
> > space, that is part of every PCI plug in card.  It is NOT part of the chip
> > set.
> > Some BIOSs let you set this number, some default to 'some' number.  This
> > register is only used for bus masters.  Usually only disk controllers and
> > network adapters provide the bus master function.  Video cards may or may
> > not.
> > The PCI revision 2.1 spec says 16 should be the maximum number.  What PCI
> > latency is, is for how many data cycles a bus master can keep the bus once
> > it has been granted permission to use the bus.  If you set it to high,
> > other cards may not get the bus in time, and may loose data.  Honestly, I
> > wouldn't believe there would be a problem setting it to 32, but I wouldn't
> > set it to much higher than that.
> > Austin Franklin

> When I first looked at my PCI latency setting (before any adjustment) it
> was set to "66."  This is much higher than your suggested 32 and that
> was the factory setting.  I adjusted it to "90" and my DMAtest scores
> went up to "93.5 MB/sec" and no resulting problems have occured.
> --
> Matt Lewis


Mine too is set to 66, factory setting. But my bios book says i shouldnt
change it,
will it***ought if i do increase it, will nt 4.0 die?
--Sam
Austin Frankli

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Austin Frankli » Sat, 08 Feb 1997 04:00:00

Mat,

The problem with these test scores is they only exercise the one thing you
are testing.  They don't let you see what the effect on the other aspects
of your system may be.  If you are testing out the speed of your video, to
see the effects on your hard disk controller, you need to run them both in
some kind of real world test, or the numbers are purely academic.  How
often to you just use your video card....all by it self...with no other
cards using the PCI bus (or the system for that matter)?

I don't think you'll see any problems going from 66 to 90.  The only time
this may effect your other cards (i.e. disk controller) is if you are doing
full motion video, and the video is being used constantly.  Then the disk
would be slower, because it can't get as much bus bandwidth as it needs.
The disk slow down could be negligable to somewhat significant, it depends
on many different things.

The tests that just test one thing, i.e. main memory speed, or DMA test
just give singular results.  Real world tests, like the ZD labs tests (ala
PC Magazine testing) give a much more accurate representation as to how the
overall system is performing.  They're free too!

Austin Franklin

Jonathan E. Schneewe

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Jonathan E. Schneewe » Sat, 08 Feb 1997 04:00:00

I have a Tomcat III w/Award 4.51PG version 4.0E
Can I change my latency settings, and if so, how?
Sincerely,
Jonathan E. Schneeweis

On 7 Feb 1997 13:53:04 GMT, "Austin Franklin"


>> When I first looked at my PCI latency setting (before any adjustment) it
>> was set to "66."  This is much higher than your suggested 32 and that
>> was the factory setting.  I adjusted it to "90" and my DMAtest scores
>> went up to "93.5 MB/sec" and no resulting problems have occured.

>Mat,

>The problem with these test scores is they only exercise the one thing you
>are testing.  They don't let you see what the effect on the other aspects
>of your system may be.  If you are testing out the speed of your video, to
>see the effects on your hard disk controller, you need to run them both in
>some kind of real world test, or the numbers are purely academic.  How
>often to you just use your video card....all by it self...with no other
>cards using the PCI bus (or the system for that matter)?

>I don't think you'll see any problems going from 66 to 90.  The only time
>this may effect your other cards (i.e. disk controller) is if you are doing
>full motion video, and the video is being used constantly.  Then the disk
>would be slower, because it can't get as much bus bandwidth as it needs.
>The disk slow down could be negligable to somewhat significant, it depends
>on many different things.

>The tests that just test one thing, i.e. main memory speed, or DMA test
>just give singular results.  Real world tests, like the ZD labs tests (ala
>PC Magazine testing) give a much more accurate representation as to how the
>overall system is performing.  They're free too!

>Austin Franklin


Michael E. Carve

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Michael E. Carve » Sat, 08 Feb 1997 04:00:00


: I have a Tomcat III w/Award 4.51PG version 4.0E
: Can I change my latency settings, and if so, how?
: Sincerely,
: Jonathan E. Schneeweis

You can't with the Award BIOS'es provided by Tyan.  I am not even sure
if their AMI BIOS have a PCI latency setting.  I have asked Tyan tech
support about this time and time again.  I have yet to receive a reply
from them about this issue.  I suggest you sent them some e-mail letting
them know you would like to have control of the PCI latency timing in
the next BIOS upgrade.  It's possible to do, other Award BIOS'es seem to
have this for the HX/VX chipset.

--
**************************** Michael E. Carver *************************
     Upside out, or inside down...False alarm the only game in town.

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=<[ /./.  [-  < ]>=-=-=-=-=-=-=-=-=-=-=-=-=-=

David Sca

PCI streaming/latency, Verite 3D accelerators and HX/VX

by David Sca » Sat, 08 Feb 1997 04:00:00



The Tyan Titan III AMI BIOS does have a PCI latency setting.
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This space intentionally left blank

Jason R Smi

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Jason R Smi » Sun, 09 Feb 1997 04:00:00

I have a Tyan S1470VX Triton III motherboard that does NOT have the
PCI Latency Setting.




>>You can't with the Award BIOS'es provided by Tyan.  I am not even sure
>>if their AMI BIOS have a PCI latency setting.  I have asked Tyan tech
>The Tyan Titan III AMI BIOS does have a PCI latency setting.
>----------------------------------------------------------------------
>This space intentionally left blank


Stuart Boo

PCI streaming/latency, Verite 3D accelerators and HX/VX

by Stuart Boo » Tue, 11 Feb 1997 04:00:00


>When I first looked at my PCI latency setting (before any adjustment) it
>was set to "66."  This is much higher than your suggested 32 and that
>was the factory setting.  I adjusted it to "90" and my DMAtest scores
>went up to "93.5 MB/sec" and no resulting problems have occured.

This is all interesting. Out of sheer curiosity after this discussion
lasted a while I went on to look at my default setting on my Asus PPro
board, an XP6NP5 - 32. All the manual states is that this is the
optimal setting for the motherboard. That's it!

Stuart

--
Stuart Booth
Somewhere in Oxfordshire, England, UK

Note: My email address is in disguise! Remove trailing Z


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