Date: Mon, 13 Dec 1999 21:52:23 +0000 (GMT) From: Doug Rabson <dfr@nlsystems.com> To: Martin Cracauer <cracauer@cons.org> Cc: arch@freebsd.org Subject: Re: Concrete plans for ucontext/mcontext changes around 4.0 Message-ID: <Pine.BSF.4.10.9912132150580.6070-100000@tecra.nlsystems.com> In-Reply-To: <19991213091915.D13197@cons.org>
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On Mon, 13 Dec 1999, Martin Cracauer wrote: > First correction: > > > - Add one int member to use as 32 bitwise booleans to indicate what > > the SSE/additional space is used for in this signal invocation. FPU > > state will unconditionally be there. > > Forgot about lazy FPU context switching (should have finished reading > my mailbox). FPU context is not always there. > > The Linux people claim that lazy FPU switching is not worth the effort > anymore on modern machines. I didn't see any proof or numbers. Anyone > of you? We currently do lazy fpu switching on alpha but since gcc likes to use FP registers for memory moves even in integer-only programs, I don't think we get much (if any) benefit from it. I haven't attempted to measure the cost/benefit though. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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