[ltt-dev] LTTng and multi-core

Klein, Russell russell_klein at mentor.com
Wed Oct 13 19:11:32 EDT 2010


I am viewing the results in lttv-gui, I have version 0.12.20.  Are you
asking me to run it in "lttv"?  I'm not sure how to run that.

There are 2 views in lttv-gui, which seem to contradict each other.  In
the "event viewer" the COREID field is the same for all events
associated with all threads created by the application.  However, in the
"control flow viewer" it shows several threads/processes as concurrently
in the "run" state.  Which I assume can only occur if the threads are on
different cores.  

I'm not sure how to interpret the "resource viewer", but it appears to
have a lot of activity on all cores during the execution of the app.
This would tend to confirm that the threads are spread across the cores,
as expected.

Thanks, Russ

-----Original Message-----
From: Mathieu Desnoyers [mailto:compudj at krystal.dyndns.org] 
Sent: Wednesday, October 13, 2010 3:51 PM
To: Klein, Russell
Cc: ltt-dev at lists.casi.polymtl.ca
Subject: Re: [ltt-dev] LTTng and multi-core

* Klein, Russell (russell_klein at mentor.com) wrote:
> An additional data point on the message forwarded by Francois
> (http://lttng.org/pipermail/ltt-dev/2010-October/003369.html) :
> I added the function sched_getcpu() to the application, so I could see
> the core id for each thread as it was launched.  The core-id as
> by the sched_getcpu does *not* match the values in the CPUID field in
> the event viewer.  It appears that the values in the event viewer are
> incorrect.

Can you try viewing your trace with the LTTV viewer and compare ?

It's available on the http://lttng.org website.



Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.

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