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From: gemini@homxb.UUCP (Rick Richardson)
Newsgroups: net.arch,net.unix-wizards
Subject: Re: IOCALL results and problems
Message-ID: <1035@homxb.UUCP>
Date: Wed, 18-Dec-85 22:00:21 EST
Article-I.D.: homxb.1035
Posted: Wed Dec 18 22:00:21 1985
Date-Received: Fri, 20-Dec-85 04:40:39 EST
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Organization: PC Research, Inc.
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Larry McVoy writes:
>I tend to agree with Dan.  I think what people would like to see is a 
>benchmark which measures how well Unix, running multiple users, performs
>on each machine.  The benchmark would have to measure something that did
>not vary widely (such as I/O devices), as those results would only reflect
>how much one had spent on the bus & disk.  So, how about this:
>
>The dryhstone benchmarks are considered good tests of the CPU (at least by 
>me they are), but don't really test Unix at all (in fact some people run 
>them in standalone mode).  How about a version, (called forkstone?), which
>runs the dryhstone as 1, 2, 8, and 64 concurrent processes?  This would
>show 1) the speed of the CPU, 2) first part of the curve, 8) a nice single
>user level, and 64) what happens when you have multiple users.  
>
>It would not test I/O, which is a hard thing to test fairly.  It would get
>rid of those Z80 dryhstones (flame, flame) as they're not multi tasking...
>
>I guess if there is any response and nobody wants to do it, I'll hack the
>drystones.  I think it would be better if the original author did it, as
>{s}he probably can understand that bastardized {C}Ada source.

I don't think that running multiple dhrystones would measure anything more
than the cost of doing a context switch once every <scheduling granularity>.
Except on a multiple processor machine, the time will be N*1 dhrystone +
M context switches.  There are easier ways to measure the time to do a context
switch.  If you want to measure multi-user response, you've GOT to open the
IO can-of-worms, since they WILL be doing IO.

Rick Richardson, PC Research, Inc. (201) 922-1134
..!ihnp4!houxm!castor!{rer,pcrat!rer} <--Replies to here, not to homxb!!!

P.S. Rheinhold Weicker is the author of Dhrystone.  I apologize for
creating the bastardized {C}Ada source from his original Ada!