linux-kernel - tracing child threads with address filtering using intel

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Message-ID: <bcc45357-fe84-05be-58c1-248efd15e3d6@gatech.edu>
Date:   Wed, 3 Oct 2018 00:19:39 +0000
From:   Mansour Alharthi <malharthi9@...ech.edu>
To:     "\"peterz@...radead.org; mingo@...hat.com; acme\"@kernel.org" 
        <"peterz@...radead.org; mingo@...hat.com; acme"@kernel.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: tracing child threads with address filtering using intel_pt pmu

Hello all,

I am having trouble tracing child threads when using address filtering 
with intel_pt ..

Assume this test code:

thread_start(){
...
test();
...
}

test(){
printf("test");
}

main(){
...
pthread_create(......, thread_start,....);
}

Tracing the above program with the following command:
perf record -v -m 512,10000 -e intel_pt//u -T --switch-events --filter 
'filter * @ ./test' -- ./test

Returns zero trace for code executed by child thread, i.e. 
thread_start() and test() functions..
While tracing without the filter does include the threads trace:
perf record -v -m 512,10000 -e intel_pt//u -T --switch-events -- ./test

Is this intended? or is it a bug?

Thanks!
Mansour.