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

From: Bryan O'Sullivan
Date: Thu Jun 29 2006 - 19:32:59 EST


On Thu, 2006-06-29 at 15:03 -0700, David Miller wrote:

> I'm not good with names :-)

Heh. I'll call it memcpy_nc for now, then, and people can retch all
over the name as they please when I submit a more suitably generic
patch.

> Note that there also might be cases where using such a memcpy
> variant might be the wrong thing to do. For example, for a very
> tightly coupled CMT cpu implementation which has the memory controller,
> L2 cache, PCI controller, etc. all on the same die and the PCI controller
> makes use of the L2 cache just like the cpu threads do, using this
> kind of memcpy would always be the wrong thing to do.

I'm not quite following you, though I assume you're referring to Niagara
or Rock :-) Are you saying a memcpy_nc would do worse than plain
memcpy, or worse than some other memcpy-like routine?

<b

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