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Date: Sat, 23 Jul 2011 13:56:55 +0200
From: Fabian Keil <freebsd-listen@fabiankeil.de>
To: Yuri <yuri@rawbw.com>
Message-ID: <20110723135655.4479d190@fabiankeil.de>
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References: <20110722202811.17302hol2s3ar084@newwebmail.rawbw.com>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: DTrace script asserts and kills the other process
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Yuri <yuri@rawbw.com> wrote:

> I am trying to run this dtrace script:
>=20
> #!/usr/sbin/dtrace -s
> pid123:libc::entry
> {
> self->timestmp[probefunc] =3D timestmp;
> }
> pid123:libc::return
> /self->timestmp[probefunc] !=3D 0/
> {
> @function_duration[probefunc] =3D sum(timestmp -
> self->timestmp[probefunc]); timestmp[probefunc] =3D 0;
> }
>=20
> which I got from here: =20
> http://www.princeton.edu/~unix/Solaris/troubleshoot/dtrace.html
> replacing 123 with the pid of some running process.
>=20
> Result: dtrace utility asserts:
> Assertion failed: (dpr !=3D NULL), file =20
> /usr/src/cddl/lib/libdtrace/../../../cddl/contrib/opensolaris/lib/libdtra=
ce/common/dt_proc.c,
> line 751.
> Abort trap: 6
>=20
> Also the target process is killed too:
> Killed: 9
>=20
> 8.2-STABLE amd64

This is a known issue. You may be able to work around it by
letting dtrace start the traced process.

There's already a PR about it:
http://www.freebsd.org/cgi/query-pr.cgi?pr=3Dbin/158431
but the limitation isn't mentioned in the wiki:
http://wiki.freebsd.org/DTrace/userland

It's not clear to me if this has worked in the past or if it
works for other architectures (the reporter and I are both using
amd64, too).

Fabian

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