Path: utzoo!attcan!uunet!husc6!mailrus!uflorida!haven!umd5!uvaarpa!babbage!mac3n
From: mac3n@babbage.acc.virginia.edu (Alex Colvin)
Newsgroups: comp.arch
Subject: Re: separate integer and float register
Summary: cheap contexts
Message-ID: <342@babbage.acc.virginia.edu>
Date: 16 Aug 88 13:17:55 GMT
References: <2724@wright.mips.COM> <6800002@modcomp>
Organization: University of Virginia
Lines: 13

> Special floating point registers also slow down context switching, due
> to the extra time needed to save/restore them.

Depends.

In some systems the FP registers are only saved if they're going
to be re-used.
In a simple interrupt handler, where you promise not to touch FP, you leave
them active.
In other environments you make certain registers global, shared by all
tasks & handlers, never saved.

This assumes a lot of control over the code.