Re: TIMEOUT - WRITE_DMA - A possible FIX! turn off ACPI

On Mon, 27 Dec 2004, Joe Koberg wrote:

> Zsolt Kúti wrote:
>
>> My system produces these messages that I already know well from this
>> list (as well ;):
>> ad4: TIMEOUT - WRITE_DMA retrying (2 retries left) LBA=213249674
>> 
>> 
> So I rebooted the freshly installed 5.3-R without ACPI, and It works!
> I can read at 50MB/s per drive concurrently (hitting PCI bus speed
> limit?), and write at 30MB/s per drive concurrently. No errors so
> far, and its been dd'ing for a half hour.

Regular PCI and PCI-X (eXtended) is:

33hmz/32bits	132 Megabyte
66mhz/32bits	264 Megabyte
66mhz/64bits	520 Megabyte
100mhz/64bits	784 Megabyte
133mhz/64bits	1040 Megabyte
etc.

With overhead included I'd say 100 Megabyte is pretty reasonable
for a normal pci bus. Keep in mind that this is for the whole bus,
which is why most server motherboard have multiple seperate busses.

PCI-X is an extension to regular pci, with more mhz/bits.
PCI-E ( Express ) is a redesign with higher speeds and fewer
traces needed. The big problem with 64bits pci is not the slot
but the fact that you have to run all those extra (fast) lines
to the slots which means that you'll need extra space
(mainly layers) to store them, ergo an expensive motherboard.

HTH, HAND.

-- 
Sten Spans

"There is a crack in everything, that's how the light gets in."
Leonard Cohen - Anthem