From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Khouzam Subject: Re: Questions about CTF format Date: Fri, 31 Aug 2012 10:34:48 -0400 Message-ID: <5040CB88.3090203__11918.291290249$1346423747$gmane$org@ericsson.com> References: <20120705142052.GA23162@Krystal> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0708983343==" Return-path: Received: from imr4.ericy.com ([198.24.6.9]) by ltt.polymtl.ca with esmtp (Exim 4.72) (envelope-from ) id 1T7SJP-0007cM-QQ for lttng-dev@lists.lttng.org; Fri, 31 Aug 2012 10:35:07 -0400 Received: from eusaamw0706.eamcs.ericsson.se ([147.117.20.31]) by imr4.ericy.com (8.14.3/8.14.3/Debian-9.1ubuntu1) with ESMTP id q7VEaxCu028080 for ; Fri, 31 Aug 2012 09:37:22 -0500 In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lttng-dev-bounces@lists.lttng.org To: lttng-dev@lists.lttng.org List-Id: lttng-dev@lists.lttng.org --===============0708983343== Content-Type: multipart/alternative; boundary="------------090809070400030407050207" --------------090809070400030407050207 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit On 12-07-05 10:49 AM, Diego Dompe wrote: > Hi Mathieu, > > Thanks for the help. Here is my list of details: > > - Clocks: the spec doesn't explain properly that timestamps are an > offset from the base time of the clock they refer to. Since I was > using 64bit timestamps I somehow assumed that I was using absolute > timestamps from the epoch (although the spec doesn't says it either). This is acceptable AFAIK, just to be clear, you can use arbitrary time origins, that means epoch is a valid origin too. You can also use a scaling factor, just be careful applying it since a double has 53 bits and thus you may lose precision. > > - I saw that the lttng-generated traces for metadata are always a > multiple of 4k in size (at least the ones I generate for either kernel > or user space). I can't find where in the spec it mentions > requirements regarding metadata packet padding. I was generating > metadata packets that ended up right after my TSDL and eclipse wasn't > happy about it (although I didn't try babeltrace). Could you send the trace please, I can look into it. > Also I found that the lttng-generated traces have a "empty" metadata > packet after the metadata containing the TSDL, I didn't find either > any documentation regarding this. > > Regards, > > Diego > > On Thu, Jul 5, 2012 at 8:20 AM, Mathieu Desnoyers > > wrote: > > * Diego Dompe (ddompe@gmail.com ) wrote: > > Hi, > > > > I'm developing a custom tracer for an embedded product that will > generate > > CTF format. I was able to generate generic traces that can be > interpreted > > properly with babeltrace (but not with eclipse, I already file a > bug for > > that), but I found the CTF specification lacking in some aspects > (I had to > > peek into lttng-generated CTF traces to figure out some > details). I was > > wondering what is the proper mailing list to clear my questions > and provide > > feedback on the CTF specification for improvement in the areas > where the > > documentation is not detailed yet. I don't see any CTF-specific > mailing > > list, it's OK to discuss it here? Or maybe directly with a > developer(s)? > > Hi Diego, > > Yes, this mailing list would be the proper place, along maybe with > adding the MCA tiwg mailing list in CC, which I'm doing here. > > Thanks, > > Mathieu > > -- > Mathieu Desnoyers > Operating System Efficiency R&D Consultant > EfficiOS Inc. > http://www.efficios.com > > --------------090809070400030407050207 Content-Type: text/html; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit
On 12-07-05 10:49 AM, Diego Dompe wrote:
Hi Mathieu,

Thanks for the help. Here is my list of details:

- Clocks: the spec doesn't explain properly that timestamps are an offset from the base time of the clock they refer to. Since I was using 64bit timestamps I somehow assumed that I was using absolute timestamps from the epoch (although the spec doesn't says it either).
This is acceptable AFAIK, just to be clear, you can use arbitrary time origins, that means epoch is a valid origin too. You can also use a scaling factor, just be careful applying it since a double has 53 bits and thus you may lose precision.

- I saw that the lttng-generated traces for metadata are always a multiple of 4k in size (at least the ones I generate for either kernel or user space). I can't find where in the spec it mentions requirements regarding metadata packet padding. I was generating metadata packets that ended up right after my TSDL and eclipse wasn't happy about it (although I didn't try babeltrace).
Could you send the trace please, I can look into it.

Also I found that the lttng-generated traces have a "empty" metadata packet after the metadata containing the TSDL, I didn't find either any documentation regarding this.

Regards,

Diego

On Thu, Jul 5, 2012 at 8:20 AM, Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
* Diego Dompe (ddompe@gmail.com) wrote:
> Hi,
>
> I'm developing a custom tracer for an embedded product that will generate
> CTF format. I was able to generate generic traces that can be interpreted
> properly with babeltrace (but not with eclipse, I already file a bug for
> that), but I found the CTF specification lacking in some aspects (I had to
> peek into lttng-generated CTF traces to figure out some details). I was
> wondering what is the proper mailing list to clear my questions and provide
> feedback on the CTF specification for improvement in the areas where the
> documentation is not detailed yet. I don't see any CTF-specific mailing
> list, it's OK to discuss it here? Or maybe directly with a developer(s)?

Hi Diego,

Yes, this mailing list would be the proper place, along maybe with
adding the MCA tiwg mailing list in CC, which I'm doing here.

Thanks,

Mathieu

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com


--------------090809070400030407050207-- --===============0708983343== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev --===============0708983343==--