Subject: Re: 5184 bottles of sends on the wall...

From: Tony Skjellum <[email-masked]>
Date: Thu, 4 Feb 93 09:25:56 CST

Please remember that overlapped send/receive will only make sense on
systems with excess memory bandwidth.  Hence, it might make more sense
to implement a system where this is permitted by the implementor, but
not required.  Otherwise, calculations might slow down instead of
achieving pipelined improvements.  As Al points out, it is only the
heavy-duty guys who try this sort of stuff...

- Tony

---

From: [email-masked] (James Cownie)
Date: Thu, 4 Feb 93 15:44:56 GMT

> achieving pipelined improvements.  

True, and all the more reason to avoid as many copies as possible.
After all if taking it from the user buffer consumes bandwidth 1, then
the bandwidth cost of a send which needed a copy will be 2+1 = 3. This
can be significant.

(Of course I'm assuming a "fair" memory system here, in which taking
from one port only loses the same from another. I've seen systems
where this wasn't true, and this can change the balance.)

-- Jim
James Cownie 
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