Xref: utzoo comp.lang.c:14491 comp.lang.misc:2269
Path: utzoo!utgpu!watmath!clyde!att!rutgers!gatech!ukma!nrl-cmf!ames!haven!ncifcrf!nlm-mcs!adm!smoke!gwyn
From: gwyn@smoke.BRL.MIL (Doug Gwyn )
Newsgroups: comp.lang.c,comp.lang.misc
Subject: Re: instruction timings (was: Assembly or ....)
Message-ID: <9045@smoke.BRL.MIL>
Date: 2 Dec 88 17:17:00 GMT
References: <1388@aucs.UUCP> <729@convex.UUCP> <1961@crete.cs.glasgow.ac.uk> <1988Nov29.181235.23628@utzoo.uucp> <960@vsi.COM>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) )
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 12

In article <960@vsi.COM> friedl@vsi.COM (Stephen J. Friedl) writes:
>Why is this?  When I was hacking on the VAX, nobody could ever
>tell me how long anything took, and empirical measurements were
>pretty tedious.  Is it laziness on the vendor's part or are there
>good reasons for this?

Exact computations of instruction timings, already quite difficult
for the VAX-11/780, have become so context-dependent as to be not
worth attempting.  Time taken for a given instruction depends on
such things as cache hit rate, fault rate, instruction mix, and so
forth.  What really matters is overall system performance, which
is a statistical matter.