Link to information about the i850 restricted PCI bandwidth issue?

[CZroe]

I remember reading about it here somewhere LOOOONG ago.

Can anyone get me that information again? I tried Google.

Edit: Found it.

Page 12, errata 5

"Intel® 82850/82850E MCH

5. Sustained PCI Bandwidth
Problem: During a memory read multiple operation, a PCI master will read more than one complete cache
line from memory. In this situation, the MCH pre-fetches information from memory in order to
provide optimal performance. However, the MCH cannot provide information to the PCI master
fast enough. Therefore, the Intel® 82801BA terminates the read cycle early to free up the PCI bus
for other PCI masters to claim.
Implication: The early termination limits the maximum bandwidth to ~90 MB/s.
Workaround: None
Status: There are no plans to fix this erratum."

So the i850 and i850E are limited to less than 90MB/s (Less after PCI overhead). Sucks. My D850GB file server is probably going to have trouble with Gigabit + RAID5 Time to make a post about that...

 

[CZroe]

Originally posted by: CZroe
I remember reading about it here somewhere LOOOONG ago.

Can anyone get me that information again? I tried Google.

Found this. These people are using a similar configuration and are possibly running into an issue with it. Someone is requesting the documents just like I am. A little help?

 

[CZroe]

Yet more indication that the information has been pulled/forgotten

It's from a Tech Report comment on a Via PCI bus bandwidth issue in response to another person talking about i860 PCI bus flaws. The link no longer works.

AG #46 here.

http://developer.intel.com/design/chipsets/specupdt/29071501.pdf

Page 12, errata 5.


" No fix planned "


Havent looked at the i850 one (links got a bit wrong BTW) but i think youll find it the same.

Help!

 

[mikecel79]

Here's the i850 document. Linky. Looks like it has the same problem as the i860.

 

[CZroe]

Originally posted by: mikecel79
Here's the i850 document. Linky. Looks like it has the same problem as the i860.

Thnx. I had *just* found it (After I realized that the Red "X" on the other PC was because it wasn't reading PDF's properly).

May it remain in the Anandtech archives from this point forward