Network card [LWN.net]

Network card

Posted Nov 3, 2010 22:35 UTC (Wed) by cma (subscriber, #49905)
Parent article: KS2010: Linux at NASDAQ

"Evidently there are cards out there which can push incoming data directly into the processor cache, cutting out stalls caused by cache misses".

Any idea which card are those?

Thanks!

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Network card

Posted Nov 4, 2010 0:17 UTC (Thu) by cma (subscriber, #49905) [Link]

OK...found the tacnology term: DCA (Direct Cache Access)

One example: http://www.dell.com/downloads/global/products/pwcnt/en/nic-intel-gb-et-brief.pdf

Network card

Posted Nov 4, 2010 15:39 UTC (Thu) by i3839 (guest, #31386) [Link]

See http://daniel.haxx.se/blog/2008/12/18/10g-and-direct-cach...
It's also known as I/OAT.

To quote bgoglin:

> DCA doesnt really reduce the memory bandwidth requirements since the
> data still has to be fetched by the cache from the main memory (the
> device doesnt write into the cache, it just tells the cache that data
> should be fetched). The whole point of the approach is that this fetch
> is done in advance, so you dont have to wait for it when the host starts
> processing the packet.

So it doesn't seem that good yet.

With integrated memory controllers I would think it's easy to do this automatically, or at least very easily, by directly going to the cache first instead of through RAM (at least the L3 cache).