Date: Thu, 14 Jun 2012 09:00:45 -0700 From: George Neville-Neil <gnn@neville-neil.com> To: Fabian Keil <freebsd-listen@fabiankeil.de> Cc: freebsd-current@freebsd.org, Ryan Goodfellow <rgoodfel@eecs.wsu.edu> Subject: Re: DTrace broken on 9.0-Release? Message-ID: <5BD5B2B1-7165-4705-8750-50EEBB5E26F2@neville-neil.com> In-Reply-To: <20120614115301.1cd0975b@fabiankeil.de> References: <5D6510D5-A8B3-41D9-B175-15FA680AF7F2@eecs.wsu.edu> <20120614115301.1cd0975b@fabiankeil.de>
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Top post. File a PR and assign it to me (gnn) please. I'm on vacation until Sunday but I am actively working on DTrace when I'm not on vacation. Best, Geo On Jun 14, 2012, at 02:53 , Fabian Keil wrote: > Ryan Goodfellow <rgoodfel@eecs.wsu.edu> wrote: > >> 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 = 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 >> 0 188748 malloc:entry >> 0 188748 malloc:entry >> 0 188748 malloc:entry >> 0 188748 malloc:entry >> >> (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 >> >> and the execution does either not exit on it's own or hangs, it requires >> a ctrl-c. > > Doesn't work for me either on 10-CURRENT amd64. > Converting it to C doesn't make a difference, it works if > one changes the loop to "for (;;)", though. > >> 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. > > In my opinion the problem with DTrace on FreeBSD is that while it's > known to be incomplete, there doesn't seem to be documentation > available about which parts are supposed to work already and which > aren't. > > For example the trivial example program at: > http://wiki.freebsd.org/DTrace/userland (which works for me) doesn't > actually use a counting loop, so maybe dtracing your example program > isn't supposed to work yet and never did on FreeBSD. > > Without documentation it's hard to tell. > > Fabian
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