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From: reiter@endor.harvard.edu (Ehud Reiter)
Newsgroups: comp.arch
Subject: Re: Towards A Meaningful Performance Measure
Message-ID: <3141@husc6.UUCP>
Date: Mon, 9-Nov-87 16:17:37 EST
Article-I.D.: husc6.3141
Posted: Mon Nov  9 16:17:37 1987
Date-Received: Wed, 11-Nov-87 06:48:21 EST
References: <861@winchester.UUCP> <2993@phri.UUCP>
Sender: news@husc6.UUCP
Reply-To: reiter@harvard.UUCP (Ehud Reiter)
Organization: Aiken Computation Lab Harvard, Cambridge, MA
Lines: 35
Keywords: benchmarks

In article <7786@steinmetz.steinmetz.UUCP> davidsen@crdos1.UUCP (bill davidsen) writes:
>In article <3113@husc6.UUCP> reiter@harvard.UUCP (Ehud Reiter) writes:
>|The problem with MIPS is that attempts to measure "integer crunching"
>|performance, and  ...
>|	(b)   In any case, not many customers care about integer crunching
>|performance.
>
>Here I don't feel that you are correct... machine usage seems to fall
>into two categories of user, the "number crunchers" who need f.p.
>performance, and the rest of the software development, word processing,
>E-mail, record keeping world. The speed of integer arithmetic is *very*
>important to most groups.

My own impression has been that people doing the above tasks care more
about I/O performance (speed of terminals, disks, etc) than CPU performance.
The main exception to this is that people want the OS to quickly perform the
bookkeeping overhead associated with doing I/O (many systems are more
limited by the speed at which the OS can do the bookkeeping than the actual
speed at which the I/O devices perform).

However, since different machines have vastly different OS's, MIPS ratings
(or any hardware-only performance measure) gives very little insight into
how quickly machines can do I/O bookkeeping.  Machine X could perform integer
adds at half the speed of machine Y, but still be able to maintain an I/O
throughput rate that was ten times as high as machine Y, simply because X
had an OS which was much better suited to the application.

So, what I'm saying is that what I believe most people care about is not raw
hardware integer compute speed, but the speed at which the OS can perform
its chores, and there is not necessarily much correlation between the two
numbers.

					Ehud Reiter
					reiter@harvard	(ARPA,BITNET,UUCP)
					reiter@harvard.harvard.EDU  (new ARPA)