From: Ralf Baechle <ralf@oss.sgi.com>
To: Jun Sun <jsun@mvista.com>
Cc: Greg Lindahl <lindahl@conservativecomputer.com>, linux-mips@oss.sgi.com
Subject: Re: FPU emulator unsafe for SMP?
Date: Wed, 20 Feb 2002 14:18:41 +0100 [thread overview]
Message-ID: <20020220141841.E15588@dea.linux-mips.net> (raw)
In-Reply-To: <20020219202434.F25739@mvista.com>; from jsun@mvista.com on Tue, Feb 19, 2002 at 08:24:34PM -0800
On Tue, Feb 19, 2002 at 08:24:34PM -0800, Jun Sun wrote:
> > What you propose, locking the fpu owner to the current cpu, will not
> > result in a fair solution. Imagine a 2 cpu machine with 2 processes
> > using integer math and 1 using floating point... how much cpu time
> > will each process get?
>
> In this case, proc that uses fpu gets about 50% of one cpu, i.e., 25% of
> total load, while the other two integer math proces split the rest 75%,
> which gives 37.5% each. Not too bad in my opinion.
Certainly not good either. Still not having checked the x86 solution
I currently favor the approach of only always storing the fp context
but lazily restoring it.
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
2002-02-20 4:48 ` Greg Lindahl
2002-02-20 9:27 ` Florian Lohoff
2002-02-20 13:18 ` Ralf Baechle [this message]
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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