From mboxrd@z Thu Jan  1 00:00:00 1970
From: matthew.khouzam@ericsson.com (Matthew Khouzam)
Date: Fri, 4 Feb 2011 13:59:59 -0500
Subject: [ltt-dev] LTTng and RTAI
In-Reply-To: <20110204115413.vr2a7frjyxc8sooo@secure.et-inf.fho-emden.de>
References: <20110204115413.vr2a7frjyxc8sooo@secure.et-inf.fho-emden.de>
Message-ID: <4D4C4CAF.1010303@ericsson.com>

That would be interesting to try out.

One issue with RTAI (at least that I've experienced) is that is is 
supported generally by older kernels. RTAI itself is at 3.8+ I think, so 
your kernel is probably something around 2.6.17?

 From the compatibility matrix 
(http://git.lttng.org/?p=lttv.git;a=blob_plain;f=doc/developer/lttng-lttv-compatibility.html;hb=HEAD) 

I would suggest trying the 0.6.2, the trace version would be 0.7, You 
would need LTTV version 0.8.62, TMF would not work for visualizing this.

At home I have RTAI 3.8 and an instrumented kernel works fine on it. I 
tried tracing something and it doesn't affect the latency that much. (On 
an athlon 64 3000+ my max latency passes from 40 us to 42-43 
empirically) I did not read the trace output, but the files were created 
and there were no big error messages.

I tried it during some RT apps and the apps worked properly, BUT I had a 
hard rt system that was requiring rtai but had latency requirements in 
the 500us range.

If your max latency is 50 us and your deadline is 50.01 us, you will 
have issues.

For tl;dr It should work with the right version. Works for me, try it out.


On 11-02-04 05:54 AM, babrah at et-inf.fho-emden.de wrote:
> Hi,
>
> I am wondering if LTTng is usable with RTAI 3.4. Do you know anything
> about it?
>
> kind regards,
>
> Bernd Abraham
>
>
>
>
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