Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!sun-barr!newstop!sun!aeras!elxsi!beatnix!rw
From: rw@beatnix.UUCP (Russell Williams)
Newsgroups: comp.arch
Subject: Re: Register usage
Message-ID: <2700@elxsi.UUCP>
Date: 1 Jun 89 16:28:10 GMT
References: <259@mindlink.uucp> <25382@ames.arc.nasa.gov> <m0fRx4x-0001fDC@mipon2.intel.com> <1RcY6x#64Zq3Y=news@anise.acc.com>
Sender: news@elxsi.UUCP
Reply-To: rw@beatnix.UUCP (Russell Williams)
Organization: ELXSI Super Computers, San Jose
Lines: 18

In article <1RcY6x#64Zq3Y=news@anise.acc.com> lars@salt.acc.com (Lars J Poulsen) writes:
>From a humble applications programmer, who occasionally has written a bit
>of kernel code: The biggest pain with an architecture that exposes too
>large a register file is saving and restoring on context switches. While
>interrupt service routines can ignore this and store only what they
>need, context switches require storing of the entire register set. Or do
>people really feel that the processors today are fast enough that
>scheduling pre-emption is too rare to influence the selection of
>register file size ?

   It's been my experience in working with general purpose operating systems
(not realtime monitors for embedded systems) that the register save time
is negligable compared to the other software overhead involved in a 
task or process switch. 

Russell Williams
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