From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Xenomai <xenomai@xenomai.org>
Subject: Re: [Xenomai] ipipe/x86: do not restore during context switch
Date: Wed, 06 Feb 2013 18:09:18 +0100 [thread overview]
Message-ID: <51128E3E.808@xenomai.org> (raw)
In-Reply-To: <51128CE4.4020303@siemens.com>
On 02/06/2013 06:03 PM, Jan Kiszka wrote:
> Gilles,
>
> do you remember if this core-3.4 change was a performance optimization
> or a necessary fix? Also, I'm not yet understanding why we need all the
> #ifdefs except for the first one which forces fpu.preload to 0.
It is a performance optimization, without it, we systematically hit the
maximum latency when the timer would tick during a context switch which
restores the FPU. Note that if you change that, you will probably break
-forge.
--
Gilles.
next prev parent reply other threads:[~2013-02-06 17:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-06 17:03 [Xenomai] ipipe/x86: do not restore during context switch Jan Kiszka
2013-02-06 17:09 ` Gilles Chanteperdrix [this message]
2013-02-06 17:33 ` Jan Kiszka
2013-02-06 17:35 ` Gilles Chanteperdrix
2013-02-06 17:40 ` Jan Kiszka
2013-02-06 17:44 ` Gilles Chanteperdrix
2013-02-06 17:47 ` Jan Kiszka
2013-02-06 17:51 ` Gilles Chanteperdrix
2013-02-06 18:26 ` Jan Kiszka
2013-02-06 18:31 ` Gilles Chanteperdrix
2013-02-06 18:35 ` Jan Kiszka
2013-02-06 18:40 ` Gilles Chanteperdrix
2013-02-06 19:22 ` Jan Kiszka
2013-02-06 19:30 ` Gilles Chanteperdrix
2013-02-06 19:55 ` Jan Kiszka
2013-02-06 20:03 ` Gilles Chanteperdrix
2013-02-06 20:17 ` Jan Kiszka
2013-02-06 20:20 ` Gilles Chanteperdrix
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