Newsgroups: comp.arch
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Re^2: Superlinear Speedup (was Re: Scalability?)
Message-ID: <1990Jun4.151545.10542@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1990May3.203405.23456@ecn.purdue.edu> <2075@naucse.UUCP> <6897@odin.corp.sgi.com> <49622@lanl.gov> <1990May1.154558.24009@cs.rochester.edu> <1990Jun2.080658.12651@oracle.com> <1990Jun3.145408.2472@watmath.waterloo.edu>
Date: Mon, 4 Jun 90 15:15:45 GMT

In article <1990Jun3.145408.2472@watmath.waterloo.edu> sccowan@watmsg.uwaterloo.ca (S. Crispin Cowan) writes:
>It's a theorum that (theoretically, anyway) super-linear speedup cannot
>occur.  In practice, it may occur marginally, but this is due to the
>fact that P processors have:
>	-P times as much cache
>	-P times as many data lines to their local main memory...

Don't forget that there can also be superlinear effects as fixed overhead
(not proportional to P) is handled by P processors instead of 1.
-- 
As a user I'll take speed over|     Henry Spencer at U of Toronto Zoology
features any day. -A.Tanenbaum| uunet!attcan!utzoo!henry henry@zoo.toronto.edu