From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
To: Richard Cochran <richardcochran@domain.hid>
Cc: xenomai@xenomai.org
Subject: Re: [Xenomai-core] arm ixp: more trouble with recent xenomai
Date: Mon, 11 Apr 2011 09:24:12 +0200 [thread overview]
Message-ID: <4DA2AC9C.2030607@domain.hid> (raw)
In-Reply-To: <20110411055344.GA5854@domain.hid>
Richard Cochran wrote:
> On Sun, Apr 10, 2011 at 01:22:08PM +0200, Gilles Chanteperdrix wrote:
>> Also, about the performances, Xenomai 2.4 did not have the Xenomai
>> preemptible context switches. Maybe with FCSE, it results in reduced
>> latencies to disable this option in Xenomai 2.5.
>
> So, are you saying that XENO_HW_UNLOCKED_SWITCH=n might improve
> latency?
>
> The help for this option says...
>
> This option reduces interrupt latency when costly cache and
> TLB flushes are required to switch context, and may improve
> concurrency on some SMP/multi-core systems as well.
>
> You definitely want to enable that option on embedded ARM
> platforms.
>
> so I am confused.
Is is a trade-off.
With this option enabled a context switch may be interrupted, this
improves interrupt latency, but at the expense of scheduling latency.
It makes a lot of sense without FCSE, when each context switch implies a
200us cache flush. A bit less with FCSE in guaranteed mode.
--
Gilles.
next prev parent reply other threads:[~2011-04-11 7:24 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-09 18:41 [Xenomai-core] arm ixp: more trouble with recent xenomai Richard Cochran
2011-04-09 18:55 ` Richard Cochran
2011-04-09 19:37 ` Gilles Chanteperdrix
2011-04-09 19:50 ` Gilles Chanteperdrix
2011-04-10 5:22 ` Richard Cochran
2011-04-10 6:52 ` Richard Cochran
2011-04-10 9:34 ` Gilles Chanteperdrix
2011-04-11 17:14 ` Richard Cochran
2011-04-11 21:26 ` Gilles Chanteperdrix
2011-04-12 5:43 ` Richard Cochran
2011-04-12 7:17 ` Gilles Chanteperdrix
2011-04-12 9:42 ` Richard Cochran
2011-04-12 10:00 ` Gilles Chanteperdrix
2011-04-14 16:49 ` Richard Cochran
2011-04-15 13:18 ` Gilles Chanteperdrix
2011-04-10 11:22 ` Gilles Chanteperdrix
2011-04-11 5:53 ` Richard Cochran
2011-04-11 7:24 ` Gilles Chanteperdrix [this message]
2011-04-14 16:42 ` Richard Cochran
2011-04-15 13:24 ` Gilles Chanteperdrix
2011-04-22 5:55 ` Gilles Chanteperdrix
2011-04-22 6:16 ` Gilles Chanteperdrix
2011-04-23 14:21 ` Richard Cochran
2011-04-23 15:22 ` Gilles Chanteperdrix
2011-04-24 20:15 ` Gilles Chanteperdrix
2011-04-25 6:48 ` Richard Cochran
2011-04-25 7:29 ` Gilles Chanteperdrix
2011-04-26 11:25 ` Gilles Chanteperdrix
2011-05-12 0:03 ` Gilles Chanteperdrix
2011-05-12 17:04 ` Richard Cochran
2011-04-09 19:43 ` Gilles Chanteperdrix
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