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
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