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From: ken@gvax.cs.cornell.edu (Ken Birman)
Newsgroups: comp.os.mach
Subject: Context switches? Or something else
Message-ID: <33153@cornell.UUCP>
Date: 13 Oct 89 13:03:47 GMT
Sender: nobody@cornell.UUCP
Reply-To: ken@cs.cornell.edu (Ken Birman)
Distribution: comp
Organization: Cornell Univ. CS Dept, Ithaca NY
Lines: 17

I was very interested by the two context switch postings for
the NeXT.   I notice that the NeXT benchmark uses native Mach
IPC.  Did the prior benchmark use something else (pipes, or UDP or
TCP?)

I ask because I have been interested in understanding the best
way (read best==fastest) to communicate in Mach and was unclear
on what I lose by running though UDP, rather than using Mach's
"non-standard" native scheme.  Could this 500us context switch
difference reflect a communication cost of some sort?

Has anyone done benchmarks comparing the cost of UDP, "UNIX domain"
TCP and Mach native communication for intra-machine and inter-machine
cases?  I would be very interested in seeing the figures... especially
if they covered scatter gather as well.

Ken Birman