Hi Danhua,
As has been mentioned. This functionality doesn't yet exist in the
kernel. If you post the exact code that you're working on, we can try
to suggest some alternatives. At some point, we would like an is-
enabled equivalent in the kernel.
Adam
On Nov 3, 2008, at 7:36 AM, Danhua Shao wrote:
> What I am looking for is a kernel function like "is_enabled()". This
> function can tell if DTrace is running or a Probe is enabled.
>
> With this function, my code to implement a DTrace probe would be :
>
> if ( is_enabled() ) {
> allocate memory for DTrace arguments;
> }
>
> DTRACE_PROBE(...);
>
> In this way, the heavy weight memory allocation function will not be
> called if DTrace is not enabled.
>
> Regards,
>
> Danhua
>
>
> On 11/02/08 21:32, Angelo Rajadurai wrote:
>>
>> My understanding was that the is enabled probe is only available in
>> the
>> userland for USDT probes. What Danhua wants seems to be in the
>> kernel.
>> Not sure this would work.
>>
>> -Angelo
>>
>>
>> Nikita Zinoviev wrote:
>>
>>> I do not remember exact details, but we have such functionality in
>>> dtrace support for java in JDK 7. I guess, it just looks whether
>>> nops
>>> are replaced by the breakpoint at the beginning of the probe handler
>>> (?). I suggest you ask Keith, [EMAIL PROTECTED]
>>> The idea was to give the user ability to skip heavy preprocessing of
>>> probe arguments if the probe is not enabled.
>>> As far as I know this solution for C code will be *very* efficient,
>>> (in java it involved context switching, so calling
>>> Probe::isEnabled()
>>> had nearly the same cost as actually firing the probe).
>>>
>>>
>>> Hope this helps,
>>>
>>> Nikita
>>>
>>>
>>> Danhua Shao wrote:
>>>
>>>
>>>> Hi,
>>>>
>>>> I am adding DTrace probes within NFS v3 client. In my current
>>>> implementation, I use some tsd_*() functions and kmem_zalloc()
>>>> function.
>>>> These functions might be heavy and affect the performance. I
>>>> want to
>>>> call this function only when DTrace is running or the DTrace
>>>> probes are
>>>> enable. So is there a way to check DTrace is running or DTrace
>>>> probe is
>>>> enabled?
>>>>
>>>> Regards,
>>>>
>>>> Danhua
>>>> _______________________________________________
>>>> dtrace-discuss mailing list
>>>> dtrace-discuss@opensolaris.org
>>>>
>>>>
>>> _______________________________________________
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>>>
>>>
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>
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--
Adam Leventhal, Fishworks http://blogs.sun.com/ahl
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