[ltp] PIIX vs UDMA? esp WRT vmware

[Chris Schumann]

On Mon, 14 Feb 2000, Andrew Steele wrote:
<snip>
> Could someone explain what exactly is the difference between UDMA and PIIX?
> 
> Why/Under what circumstances would you choose one over the other?

UDMA should perform better, especially when multitasking, because the CPU
load should be lower. Without DMA, IDE devices use a good deal of CPU just
waiting for data to become available, and even more moving those data to
memory. DMA bypasses all of that.

> If UDMA is the better way to go (at least from an NT perspective), why do
> IBM use PIIX?

Having had experience dealing with IBM's OEM testing group, I suspect that
they have done more testing or have fewer bugs with the PIIX code. If the
DMA chip vendor supplies the driver, they could have found the driver to
be less beneficial that it should be.

> What problems am I likely to find from using UDMA instead of IBMs preferred
> PIIX?

As long as the driver actually works (i.e. there are no bugs or
performance hiccups,) you should have no problems.

Chris Schumann <whizkid@dwave.net>

"Wait a minute, Joe. If what you're saying is true,
then I still don't care." - Dave Nelson, News Radio

----- The Linux ThinkPad mailing list -----
The linux-thinkpad mailing list home page is at:
http://www.bm-soft.com/~bm/tp_mailing.html