Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!gem.mps.ohio-state.edu!usc!venera.isi.edu!raveling
From: raveling@isi.edu (Paul Raveling)
Newsgroups: comp.os.mach
Subject: Re: Mach context switch time
Message-ID: <10304@venera.isi.edu>
Date: 27 Oct 89 18:49:40 GMT
References: <6393@imag.imag.fr> <2895@netcom.UUCP>
Sender: news@venera.isi.edu
Reply-To: raveling@isi.edu (Paul Raveling)
Organization: USC Information Sciences Institute
Lines: 37

In article <6393@imag.imag.fr>, phb@imag.imag.fr (Philippe Bernadat) writes:

> Running the same program on a NeXT and on a DS3100 I got the following
numbers:
> 
> 
> 		elapsed time for 	context switch		context switch
> 		10,000 loops		time (usec)		per second
> 
> NeXT			7.6 			380			2,631
> DS3100 (Mach 2.5)	2.3 			115			8,695

	Interesting...  Back when I first looked at Mach's native
	kernel interface my guess was that Mach would be about
	a factor of 3 faster than a "plain vanilla" Unix.  Comparing
	with the pt benchmark (vanilla kernel functions, if not
	pure vanilla kernel), shows:

					     "vanilla"	Mach	Ratio

	DS3100,  ULTRIX 2.0 R7  & Mach 2.5	390	115	3.4
	DS3100,  ULTRIX 2.1 R14 & Mach 2.5	230	115	2.0
	NeXt,	 Mach:  Version not noted	873	380	2.3
	NeXt,	 Mach:  NeXt 1.0		920	380	2.4


	Another milestone is that the 3100 Mach benchmark is the first
	context switch time I've heard reported that's faster than either:

	    170 microseconds  --  PDP-11/45 running EPOS
	    140 microseconds  --  4 MHz Z-80 running a cut-down variant
					of an EPOS kernel


----------------
Paul Raveling
Raveling@isi.edu