From: Daniel Jacobowitz <dan@debian.org>
To: Greg Lindahl <lindahl@keyresearch.com>
Cc: Jun Sun <jsun@mvista.com>, linux-mips@linux-mips.org
Subject: Re: [RFC] FPU context switch
Date: Tue, 17 Sep 2002 15:38:20 -0400 [thread overview]
Message-ID: <20020917193820.GA28255@nevyn.them.org> (raw)
In-Reply-To: <20020917120310.A2043@wumpus.internal.keyresearch.com>
On Tue, Sep 17, 2002 at 12:03:10PM -0700, Greg Lindahl wrote:
> On Tue, Sep 17, 2002 at 11:48:31AM -0700, Jun Sun wrote:
>
> > I think this gives a big performance improvement because most processes
> > don't use FPU during their runs but they all have used_math flag set!
>
> Jun,
>
> You really ought to prove that first. Many people spend a lot of time
> optimizing things that aren't important. If it isn't important, than
> the simplest scheme is the best choice.
Oh, he's quite correct. There's a setjmp() early in the execution
path, and it saves FP registers on machines with FP support configured
on. So tasks are marked as FPU users.
I've never thought of a terribly good way around this.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
next prev parent reply other threads:[~2002-09-17 19:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-17 18:04 [RFC] FPU context switch Jun Sun
2002-09-17 18:31 ` Greg Lindahl
2002-09-17 18:35 ` Jun Sun
2002-09-17 18:42 ` justinca
2002-09-17 18:48 ` Jun Sun
2002-09-17 19:03 ` Greg Lindahl
2002-09-17 19:38 ` Daniel Jacobowitz [this message]
2002-09-17 21:44 ` Dominic Sweetman
2002-09-17 21:58 ` Matthew Dharm
2002-09-17 21:58 ` Matthew Dharm
2002-09-17 22:30 ` Kevin D. Kissell
2002-09-17 22:30 ` Kevin D. Kissell
2002-09-17 22:58 ` Greg Lindahl
2002-09-17 23:03 ` Jun Sun
2002-09-17 23:44 ` Kevin D. Kissell
2002-09-17 23:44 ` Kevin D. Kissell
2002-09-17 23:45 ` Jun Sun
2002-09-18 8:38 ` Kevin D. Kissell
2002-09-18 8:38 ` Kevin D. Kissell
2002-09-18 16:53 ` Jun Sun
2002-09-18 8:29 ` Carsten Langgaard
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