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Re: [RFC] FPU context switch

To: Jun Sun <>
Subject: Re: [RFC] FPU context switch
From: Dominic Sweetman <>
Date: Tue, 17 Sep 2002 22:44:12 +0100
In-reply-to: <>
Original-recipient: rfc822;
References: <>
Jun Sun ( writes:

> 1) always blindly save and restore during context switch (switch_to())

Just a suggestion...

> Not interesting.  Just list it here for completeness.

Agreed, it's not interesting.

But it would work, every time; while the current scheme has been a
fertile source of interesting bugs.  How much useful optimisation
might have been done with the effort required to fix them?

Saving all the FPU registers on a 400MHz CPU takes about a tenth of a
microsecond.  Does anyone reading this list have evidence that this is
ever any kind of problem?

Dominic Sweetman
MIPS Technologies.

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