From: Philippe Gerum <rpm@xenomai.org>
To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: xenomai-core <xenomai@xenomai.org>
Subject: Re: [Xenomai-core] Nocow patch.
Date: Fri, 19 Jan 2007 10:58:53 +0100 [thread overview]
Message-ID: <1169200733.3964.29.camel@domain.hid> (raw)
In-Reply-To: <45B08DCF.3000708@domain.hid>
On Fri, 2007-01-19 at 10:22 +0100, Gilles Chanteperdrix wrote:
> Gilles Chanteperdrix wrote:
> > However, after looking at the ARM patch, I am not so sure
> > __ipipe_update_all_pinned_mm() is the way to go on all architectures.
> > The ARM I-pipe handles vmalloc and ioremap faults without causing a mode
> > switch, I wonder if it is not better than having
> > __ipipe_update_all_pinned_mm() updating page directories all over the
> > place.
>
> I checked with the I-pipe tracer the overhead on an ARM of a fault on a
> vmalloced area: it costs around 5 us.
>
What is the average latency in user-space on this board for 1Khz and
10Khz periods?
Beyond that, we may want to keep both approaches at hand in the core
infrastructure; running the same benchmark on, say an integrator, may
give much higher latencies due to lousy cache issues. This still needs
to be verified though.
--
Philippe.
next prev parent reply other threads:[~2007-01-19 9:58 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-10 18:05 [Xenomai-core] Nocow patch Gilles Chanteperdrix
2007-01-11 7:38 ` Niklaus Giger
2007-01-11 8:43 ` Gilles Chanteperdrix
2007-01-11 8:46 ` Gilles Chanteperdrix
2007-01-11 15:18 ` Gilles Chanteperdrix
2007-01-13 18:57 ` Philippe Gerum
2007-01-15 10:48 ` Gilles Chanteperdrix
2007-01-19 9:22 ` Gilles Chanteperdrix
2007-01-19 9:58 ` Philippe Gerum [this message]
2007-01-19 10:10 ` Gilles Chanteperdrix
-- strict thread matches above, loose matches on Subject: below --
2007-01-31 8:37 Gilles Chanteperdrix
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