[lttng-dev] Strange result from LTTng porting to ARM

[J Lin]

Hello Mathieu,

We have resolved the problem. It was a problem of IP protection that
prevented us from acessing certain memory addresses. Now investigating
problems with live tracing > Error: Unable to reach lttng-relayd. Will open
another thread if the problem persists.

Thanks,
MIKE

2014-11-18 0:53 GMT+08:00 Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
:

> Hi,
>
> There is little we can do without information about the kernel
> customization that have been done in your use-case. Most likely,
> there might be one customization that breaks tracepoints located
> in the core kernel. It appears that only the tracepoints present in
> the lttng-module modules are traced.
>
> Just as a guess, do you have CONFIG_JUMP_LABEL=y
> in your config ? Try setting it to "n'. Just in case they would
> happen to be broken on your specific kernel version/customization.
>
> Good luck!
>
> Mathieu
>
> ------------------------------
>
> *From: *"J Lin" <jmlin.jmlin at gmail.com>
> *To: *"Daniel Thibault" <Daniel.Thibault at drdc-rddc.gc.ca>
> *Cc: *lttng-dev at lists.lttng.org
> *Sent: *Thursday, November 13, 2014 6:12:14 AM
> *Subject: *Re: [lttng-dev] Strange result from LTTng porting to ARM
>
>
> Hello Daniel,
>
> I should correct myself and say cross compiled LTTng to run on ARM. We
> installed lttng-modules via insmod and verified with lsmod. Regarding
> lttng-modules, there was a problem compiling where duplicate definition
> occurred. We use kernel version 3.8 and in the source code saw the
> conflicting section "should be" guarded for version less than 3.15. So we
> added version check to work around it.
>
> We have not tested ust yet. But have compiled all three (lttng-ust,
> lttng-tools, lttng-modules) and placed on development board. Right now, we
> are just doing a simple trace for a certain irq that triggers every 4ms.
> This is the most information we got:
> [00:01:36.985006316] (+0.001175688) (none) lttng_statedump_interrupt: {
> cpu_id = 0 }, { irq = 29, name = "GIC", action = "twd" }
>
> Also noticed this when creating a session:
> [ 2][   64.512057] ##### send signal SIG : 10,
> lttng-sessiond(373)->lttng(262) __send_signal
>
> Thanks,
> MIKE
>
> 2014-11-13 3:10 GMT+08:00 Thibault, Daniel <
> Daniel.Thibault at drdc-rddc.gc.ca>:
>
>> ----------------------------------------------------------------------
>> Date: Wed, 12 Nov 2014 23:26:41 +0800
>> From: J Lin <jmlin.jmlin at gmail.com>
>>
>> > I've recently ported LTTng to ARM and I can't seem to understand what
>> is going wrong with my results. I ran a typical session with "lttng
>> enable-event -k -a" for test. Here are the observations:
>> >
>> > 1. only "lttng_xxx (e.g, lttng_statedump_interrupts)" are recorded 2.
>> different sessions yield trace on different CPU (the system has 4) but not
>> for all 4, just 1 cpu 3. no recorded session span more than 1 second though
>> I would run sleep (i.e., 10s) between "start" and "stop"
>> >
>> > This leads me to believe LTTng might be dependent on something in the
>> system that isn't present. This is a customized kernel of a client. It has
>> all required configs.
>> >
>> > If there is a trigger mechanism after running "lttng start", what would
>> it be? It seems it grabs items initially then doesn't continue. I read in
>> one of the papers that LTTng is architecture dependent. Any help is
>> appreciated.
>> >
>> > Mike
>>
>>    How exactly did you "port" LTTng to ARM?  As far as I know, you need
>> only rebuild it there.  Your symptoms lead me to believe you may have not
>> installed the requisite lttng-modules.  Did you test user-space tracing?
>>
>> Daniel U. Thibault
>> Protection des systèmes et contremesures (PSC) | Systems Protection &
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>
>
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>
> --
> Mathieu Desnoyers
> EfficiOS Inc.
> http://www.efficios.com
>
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