Well, with a little research, I believe I was able to find the answer to
determine what was available in Mac OS X.
Just execute: nm -j /mach_kernel
and, of course, one can do: nm -j /mach_kernel | grep dtrace
to see which ones are dtrace related. As expected, dtrace_nprobes &
dtrace_probes aren't in the list. I didn't see anything that looked promising,
but perhaps someone else may be able to spot something.
I am wondering...let's say I did see something that looked promising, how would
I go about determining the structure? How would I know that I could do <some
var>->something and see some meaningful data? How might someone who didn't
already know, know that dtpr_name was part of dtrace_probes[i] - i.e. that one
could do `dtrace_probes[i]->dtpr_name? Is the only way by inspecting the kernel
code itself or is thing kind of thing documented somewhere?
Thank you.
On Jun 21, 2011, at 4:12 PM, Eric Gorr wrote:
> Thanks. This is quite interesting. I wonder where one goes to learn about
> what kernel symbols are available in Mac OS X...?
>
> On Jun 21, 2011, at 12:17 PM, Adam Leventhal <a...@delphix.com> wrote:
>
>> Hey Eric,
>>
>> There's not a great way to do it, but you can use a tool like mdb(1)
>> on Solaris, or a simple DTrace script:
>>
>> ---8<--- dtrace_probes.d ---8<---
>>
>> #!/usr/sbin/dtrace -s
>>
>> #pragma D option quiet
>>
>> int i;
>>
>> tick-100
>> /i >= `dtrace_nprobes/
>> {
>> exit(0);
>> }
>>
>> tick-100
>> { printf("%4d %10s %20s %20s %10s %s\n", i,
>> stringof(`dtrace_probes[i]->dtpr_provider->dtpv_name),
>> stringof(`dtrace_probes[i]->dtpr_mod),
>> stringof(`dtrace_probes[i]->dtpr_func),
>> stringof(`dtrace_probes[i]->dtpr_name),
>> `dtrace_probes[i]->dtpr_ecb != NULL ? "enabled" : "disabled");
>> i++
>> }
>>
>> ---8<--- dtrace_probes.d ---8<---
>>
>> 0 dtrace BEGIN disabled
>> 1 dtrace END disabled
>> 2 dtrace ERROR enabled
>> 3 python589 libpython2.6.so.1.0 PyEval_EvalFrameEx
>> function-entry disabled
>> 4 python589 libpython2.6.so.1.0 dtrace_entry
>> function-entry disabled
>>
>> Unfortunately this doesn't work on Mac OS X:
>>
>> # dtrace -n 'BEGIN{ trace(`dtrace_nprobes); }'
>> dtrace: invalid probe specifier BEGIN{ trace(`dtrace_nprobes); }: in
>> action list: failed to resolve `dtrace_nprobes: Unknown symbol name
>>
>> Some kernel symbols seem to be available; perhaps someone more
>> familiar with Mac OS X can get this script running over there.
>>
>> Adam
>>
>> On Tue, Jun 21, 2011 at 5:01 AM, Eric Gorr <mail...@ericgorr.net> wrote:
>>> If it matters, I am using Mac OS X 10.6.x.
>>>
>>> Let's say that I open a terminal window, enabled a few probes, and start
>>> collecting data.
>>>
>>> From a different terminal window can I ask DTrace what probes have been
>>> enabled? If so, how?
>>>
>>> Thank you.
>>> _______________________________________________
>>> dtrace-discuss mailing list
>>> dtrace-discuss@opensolaris.org
>>>
>>
>>
>>
>> --
>> Adam Leventhal, Delphix
>> http://dtrace.org/blogs/ahl
>>
>> 275 Middlefield Road, Suite 50
>> Menlo Park, CA 94025
>> http://www.delphix.com
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