From: Ralf Baechle <ralf@oss.sgi.com>
To: Daniel Jacobowitz <dan@debian.org>
Cc: Jun Sun <jsun@mvista.com>,
Greg Lindahl <lindahl@conservativecomputer.com>,
linux-mips@oss.sgi.com
Subject: Re: FPU emulator unsafe for SMP?
Date: Wed, 20 Feb 2002 14:24:16 +0100 [thread overview]
Message-ID: <20020220142416.F15588@dea.linux-mips.net> (raw)
In-Reply-To: <20020219233222.A22099@nevyn.them.org>; from dan@debian.org on Tue, Feb 19, 2002 at 11:32:22PM -0500
On Tue, Feb 19, 2002 at 11:32:22PM -0500, Daniel Jacobowitz wrote:
> > If you do use floating point, I think it is pretty common to have
> > only process that uses fpu and runs for very long. In that case,
> > leaving FPU owned by the process also saves quite a bit.
>
> Not true. For instance, on a processor with hardware FPU, setjmp()
> will save FPU registers. That means most processes will actually end
> up taking the FPU at least once.
The cleassic reason to take the FPU is the ctc1 $0, $31 instruction used
to initalize the FPU control register rsp. it's equivalent on other
architectures. This should be fixed in glibc since a few years.
Ralf
next prev parent reply other threads:[~2002-02-20 15:00 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-15 1:56 FPU emulator unsafe for SMP? Jun Sun
2002-02-15 2:11 ` Ralf Baechle
2002-02-15 7:20 ` Jun Sun
2002-02-15 8:30 ` Jun Sun
2002-02-15 9:59 ` Kevin D. Kissell
2002-02-15 9:59 ` Kevin D. Kissell
2002-02-19 22:05 ` Jun Sun
2002-02-19 22:19 ` Ralf Baechle
2002-02-20 0:08 ` Kevin D. Kissell
2002-02-20 0:08 ` Kevin D. Kissell
2002-02-20 1:12 ` Jun Sun
2002-02-20 3:28 ` Greg Lindahl
2002-02-20 4:24 ` Jun Sun
2002-02-20 4:32 ` Daniel Jacobowitz
2002-02-20 9:48 ` Jun Sun
2002-02-20 10:14 ` Kevin D. Kissell
2002-02-20 10:14 ` Kevin D. Kissell
2002-02-20 13:50 ` Ralf Baechle
2002-02-20 20:53 ` Greg Lindahl
2002-02-20 13:24 ` Ralf Baechle [this message]
2002-02-20 4:48 ` Greg Lindahl
2002-02-20 9:27 ` Florian Lohoff
2002-02-20 13:18 ` Ralf Baechle
2002-02-20 9:56 ` Geert Uytterhoeven
2002-02-20 11:14 ` Kevin D. Kissell
2002-02-20 13:10 ` Ralf Baechle
2002-02-20 8:27 ` Dominic Sweetman
2002-02-20 9:30 ` Florian Lohoff
2002-02-20 13:56 ` Ralf Baechle
2002-02-20 13:09 ` Ralf Baechle
2002-02-20 14:42 ` Kevin D. Kissell
2002-02-20 14:42 ` Kevin D. Kissell
2002-02-20 14:46 ` Maciej W. Rozycki
2002-02-20 15:05 ` Ralf Baechle
2002-02-20 15:45 ` Maciej W. Rozycki
2002-02-20 13:03 ` Ralf Baechle
2002-02-15 8:14 ` Kevin D. Kissell
2002-02-15 8:14 ` Kevin D. Kissell
2002-02-15 10:57 ` Ralf Baechle
2002-02-19 22:02 ` Jun Sun
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