From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 13 Jan 2015 21:39:58 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Message-ID: <20150113203958.GL21032@hermes.click-hack.org>
References: <CAPozGfnFbPgfhi-ennhT2Ba=HJqs25W3WWVewXjBVbo87D81iQ@mail.gmail.com>
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In-Reply-To: <CAPozGfnFbPgfhi-ennhT2Ba=HJqs25W3WWVewXjBVbo87D81iQ@mail.gmail.com>
Subject: Re: [Xenomai] Negative latencies
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To: John Sini <jhnsini@gmail.com>
Cc: xenomai@xenomai.org

On Tue, Jan 13, 2015 at 06:01:54PM +0100, John Sini wrote:
> Hello,
> 
> 
> I was trying to boot linux with Xenomai on the Zedboard from Xilinx. When I
> run the latency test I get negative values. I tried to calibrate my system
> by running the following
> echo 1 > /proc/xenomai/latency
> 
> 
> But then when I run
> 
> cat latency - I get 0. I also get 0 if I put 2 or 3ns. If I put 4 i.e.
> 
> echo 4 > /proc/xenomai/latency and then do:
> 
> cat latency - I get 3.
> 
> Is there a possibility to calibrate my system to 1ns? Can the calibration
> be done without echo 1 > /proc/xenomai/latency somehow in latency.c. Before
> doing any calibration latency that I get is 9498.

See:
https://xenomai.org/pipermail/xenomai/2007-May/009063.html

-- 
					    Gilles.