RE: Pci to Pci transfers

[Jim Ulrich <jimu@pathlight.com>]

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From: 	Herve Suquet[SMTP:hsu@ocegr.fr]
Sent: 	Wednesday, September 11, 1996 3:07 AM
To: 	Mailing List Recipients
Subject: 	Pci to Pci transfers

Hello PCI expert,
....
I received two answers. One saying that it is obvious to do and without risks
and one saying that a lot of problem have to be faced-up making this
almost impossible to run on various PC platforms.

Between these two answers, where is the good one ?

With best regards,
Herve



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Herve,
	At Pathlight we do a lot with direct transfer from one PCI device
(ours) to another without host intervention. The caveats we have are:

	1]	The host should be 2.1 compliant if any of these devices
		is behind a P2P bridge (as many of ours are).

	2]	If the PCI devices are in a Power-MAC (or clone) then use
		of the MWI MRM MRL commands are needed to get ANY sort
		of reasonable performance.

    In a product that I just finished bringing up we have several PCI
devices behind a DEC bridge. A majority of the traffic is between
these devices, with virtually no transfers to/from the host. This
eliminates host arbitration and bandwidth bottle-necks.

Jim Ulrich
jimu@pathlight.com

My brain cells are my own and do not reflect those of my company...


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