:Hmm, I've just played around a bit, it seems we are hit by interrupt
:latency or something, if you limit the transfer to 128k, which allows
:the ATA controller to fetch it in one go, you will see the expected
:transfer rates. Now I dont see this on PCI based controllers, and that
:hints that the problem could be the fact that the two onboard controllers
:sits on irq 14 & 15 making them the lowest priority devices in the system,
:and that could cause the interrupt latency I'm seeing which then again
:causes the bad transfer rates on transfers that need to transfer more
:that one transaction full of data (ie max 128k).
:
:-Søren
The larger transfers are probably choking the IDE drive's pipelining
capabilities. That's my guess, anyway. I avoid IDE like the plague.
-Matt
Matthew Dillon
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