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Date:      Wed, 13 Jun 2012 21:33:01 -0700
From:      Ryan Goodfellow <rgoodfel@eecs.wsu.edu>
To:        freebsd-current@freebsd.org
Subject:   DTrace broken on 9.0-Release?
Message-ID:  <5D6510D5-A8B3-41D9-B175-15FA680AF7F2@eecs.wsu.edu>

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Hi FreeBSD community,

Today I downloaded and installed FreeBSD 9.0-RELEASE and followed the =
directions from <http://wiki.freebsd.org/DTrace>; to get DTrace up and =
running.  The output of DTrace instrumenting a simple program, however, =
is not correct.  The program is as follows:

// test.cc
#include<cstdlib>

int main(void) {
  for(int i =3D 0; i < 5; i++) {
    malloc(47);
  }
}

then compiling and running DTrace as follows:

g++ test.cc -o test

dtrace -n 'pid$target::malloc:entry{ }' -c ./test


The correct output for this example is something to the tune of:

dtrace: description 'pid$target::malloc:entry' matched 2 probes
dtrace: pid 95236 has exited
CPU     ID                    FUNCTION:NAME
  0 188748                     malloc:entry=20
  0 188748                     malloc:entry=20
  0 188748                     malloc:entry=20
  0 188748                     malloc:entry=20
  0 188748                     malloc:entry=20

(this from a machine with the same code running DTrace)

The DTrace session should also make an immediate exit on completion. On =
FreeBSD I have the following
CPU     ID                    FUNCTION:NAME
  2      42213                     malloc:entry=20

and the execution does either not exit on it's own or hangs, it requires =
a ctrl-c.

I followed the instructions from the FreeBSD site exactly, compiling and =
installing the custom kernel.  I used both clang++ and g++ for =
compilation with the same result.  The system has even completely hung =
on other attempts.

Is DTrace not something that should be relied upon in FreeBSD?  I have =
also tried this on the latest 10-CURRENT build with the same result.

Thanks

Ryan G=



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