Path: utzoo!yunexus!geac!syntron!jtsv16!uunet!seismo!esosun!cogen!celerity!jjw
From: jjw@celerity.UUCP (Jim )
Newsgroups: comp.arch
Subject: Re: RISC v. CISC (context switch)
Message-ID: <179@celerity.UUCP>
Date: 26 Oct 88 18:38:28 GMT
Article-I.D.: celerity.179
References: <332@pvab.UUCP>
Reply-To: jjw@celerity.UUCP (Jim (JJ) Whelan)
Organization: FPS Computing, San Diego CA
Lines: 11

In article <332@pvab.UUCP> robert@pvab.UUCP (Robert Claeson) writes:
>The more registers, the more to save at every context switch in a typical
>OS (such as UNIX). Which will slow things down if you have many processes
>running.

One solution to this is to have a "register cache" which holds the register
sets for several processes.  Context switches among the loaded processes is
then very fast.  The save/restore penalty need be paid only when a new
process is brought into the mix.  Given that there is a "locality" of
processes (processes which just ran are likely to be run again soon) this
significantly reduces the context switch cost.