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From: tve@sprite.berkeley.edu (Thorsten von Eicken)
Newsgroups: comp.arch
Subject: Re: Touchstone Delta followup
Message-ID: <1991Jun4.065526.9362@agate.berkeley.edu>
Date: 4 Jun 91 06:55:26 GMT
References: <1991Jun3.230539.7162@nntp-server.caltech.edu>
Sender: root@agate.berkeley.edu (Charlie Root)
Organization: University of California, Berkeley
Lines: 13

In article <1991Jun3.230539.7162@nntp-server.caltech.edu> jkubicky@nntp-server.caltech.edu (Joseph J. Kubicky) writes:
> I get the impression that, as the software is now written, we're talking
> at least 10us or so to actually get a message somewhere (although, as I
> also pointed out, each node can multi-task, so this delay at least need
> not contribute to wasted processing time).
So, $$$ question: how long does it *really* take to ping-pong a message
back and forth between two processors? I.e. A sends to B, B receives and
sends back, A receives and sends back, etc.. Measuring one round-trip.
I bet it's >100us.
By the way, the OS delay costs you: the processor *is* busy. No multi-tasking
changes anything to that.

	Thorsten von Eicken (tve@sprite.berkeley.edu)