Bus mastering

[smith]

Hi everybody.
on my computer, i have only Matrox G450/millenium and
a sound card. My computer is an audio related machine.
I use matrox 4 its dual outputs and reliability
So I dont really mind the display qualety.
Have been told to disable "bus mastering" in the power desk
in order to get better performance from my computer.
my question, is it really a good idea? does it have any effect
at all? my card is agp, this advice i belived to be correct only
in the case of pci cards, but i dont understand why
my agp card have this option in the p.desk at all ?

[Maggi]

disabling busmastering will cripple your performance ...

On some systems you might gain stability though, but I'm sure if you encounter problems, we'll be able to straighten those out while leaving busmastering enabled ...

How about your complete system details along with a list of your IRQ assignments ?

Cheers & welcome aboard,
Maggi

[smith]

Hi Maggi (: Thanks for your kind reply.

My Setup:
Matrox G450 millenium
Asus Cusl2-c
Intel PIII 1000
256 RAM 133 (micron)
AudioCard Creamware's Luna II (a pci hungry card)
2 Monitors (Mag,Compaq)
H.disk WD 20gb 7200

Irq assignment

00 system timer
01 standart keyboard
02 programmable interrupt controller
03 com2
04 com1
05 Luna
05 ACPI irq holder for pci irq steering
06 floppy disk
07 lpt1
08 system CMOS
09 ACPI irq holder for pci irq steering
09 ACPI irq holder for pci irq steering
10 Intel(R) 82801BA\BAM SMBus Conroller - 2443
10 ACPI irq holder for pci irq steering
11 Matrox millenium G450 DualHead english
11 ACPI irq holder for pci irq steering
12 PS/2 Compatible Mouse Port
13 Numeric data processor
14 Intel(R) 82801BA Ultra ATA storage Controller 244B
14 Primary IDE controller
15 Intel(R) 82801BA Ultra ATA storage Controller 244B
15 Secondary IDE controller (dual fifo)

ok? (: I allready disabled "bus mastering"
so far, nothing wrong happend, but nothing good either.
what is bus mastering exactly? how does it effect
my pci soundcard?
u said "on some systems you might gain stability"
can u please be more specific?

[Maggi]

your system looks properly configured ... everything in good order, so to speak ...

About busmastering:

taken from http://www.matrox.com/mga/support/fa...q/common.cfm#8

8. Does the G450 PCI support bus-mastering for non-Intel chipsets? (top)

For non-Intel chipsets, the G450 PCI does not support bus-mastering. While this lowers performance on synthetic benchmarks, it does not hinder the everyday usability of the card. Additionally, for the combination of G450 PCI and non-Intel chipsets, Open-GL acceleration and DVDMax are not supported.

Matrox has identified certain instabilities when bus-mastering is activated on the combination of non-Intel chipset and the PCI version of the Millennium G450 series (model number G45+MDHP16DB).

9. What features will not be supported for the combination of G450 PCI and non-Intel chipsets? (top)

DVDmax and OpenGL will not be supported for the combination of G450 PCI and non-Intel chipsets.

10. Will bus-mastering ever be supported with the G450 PCI cards and non-Intel chipsets? (top)

Matrox does not foresee much demand for PCI graphics products for systems with non-Intel chipsets. If Matrox releases a new version of the Millennium G450 PCI with support for such chipsets, this new version will have a different part number and its features will be clearly highlighted.

Basically the same restriction apply to your card, ie. having busmastering disabled will deactivate certain hardware acceleration and thus, if you don't experience any problems, leave it on ...

You could check out the difference for yourself by running several benchmarks, comparing both states and let us know what you found out.

Cheers,
Maggi