[ltt-dev] lttctl locks up with RT Linux

[Mathieu Desnoyers]

* jpaul at gdrs.com (jpaul at gdrs.com) wrote:
> Greetings:
> 
> I'm using a a 2.6.33.2 kernel. I have LTT up and running on the plain vanilla kernel, but "lttctl -D trace1" never returns on the RT version of the same kernel. I've downloaded and integrated the following pieces:
> 
> patch-2.6.33.2-lttng-0.211
> ltt-control-0.84-07042010
> lttv-0.12.31.04072010
> 
> Note that I've had to manually apply several of the patches from the patch file. I can provide a list if desired.
> 
> After the lockup, I can do an ls on the /tmp/trace directory and see that the following files have a non-zero length (remaining files in the trace directory have a zero length):
> 
> fs_0, fs_1, kernel_0, kernel_1
> 
> I'm running on an Intel Core2 Duo system. I've built all the LTT components into the kernel, so I do not have to load any modules at runtime. I do execute an ltt-armall prior to issuing any "lttctl -C -w /tmp/trace trace1" commands.
> 
> When the above occurs, I usually have to hard power down the machine as a root issued "reboot" does not reboot the machine (even after trying to kill the running ltt processes).
> 
> Any suggestions on how to get this working under the RT kernel would be appreciated. Does LTT even function properly for RT kernels? If not, it would be of great benefit to have it do so.  Please let me know if additional debug info would be helpful. 

I bet there is something fishy on RT with __ltt_trace_destroy(). Having
an output of where the CPU is stalled in lttng code would help.


> 
> A couple additional notes:
> 
> - LTTV docs state that it requires glib 2.4 or greater. I believe this is incorrect due to the following dependency:
> 
> $ rpm -qa glib2
> glib2-2.12.3-4.el5_3.1  << my default glib (RHEL5.x base)
> 
> state.c: In function ‘copy_process_state’:
> state.c:1344: error: ‘GHashTableIter’ undeclared (first use in this function)
> 
> I've installed glib-2.22.5 to get around the above issue.

OK, the dependency seems to be glib 2.16 now. Will update the README
and LTTng manual accordingly.

Thanks,

Mathieu


> 
> - I've upgraded to gcc-4.3.4 with the glib upgrade (along with some other dependencies).
> 
> Thanks Much
> 
> JP
> 
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-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com