Messages in this thread | | | Date | Thu, 29 Jun 2006 17:44:05 -0700 | From | Rick Jones <> | Subject | Re: [PATCH 39 of 39] IB/ipath - use streaming copy in RDMA interrupt handler to reduce packet loss |
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David Miller wrote: > From: Rick Jones <rick.jones2@hp.com> > 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?
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