Re: [PATCH 39 of 39] IB/ipath - use streaming copy in RDMA interrupt handler to reduce packet loss

David Miller wrote:

From: Rick Jones <[email protected]>
Date: Thu, 29 Jun 2006 17:28:50 -0700

I thought that most PCI controllers (that is to say the things bridging PCI to the rest of the system) could do prefetching and/or that PCI-X (if not PCI, no idea about PCI-e) cards could issue multiple transactions anyway?

People doing deep CMT chips have found out that all of that
prefetching and store buffering is unnecessary when everything is so
tightly integrated.

Then is prefetching in memcpy really that important to them (BTW besides Sun/Niagra who are doing "deep CMT"?)

All of the previous UltraSPARC boxes before Niagara had a
streaming cache sitting on the PCI controller.  It basically
prefetched for reads and collected writes from PCI devices
into cacheline sized chunks.

The PCI controller in the current Niagara systems has none of that
stuff.

Relying on PCI-X devices to issue multiple requests then?

rick jones
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