Hi,
I was reviewing the omniti labs dtrace functions, at
http://labs.omniti.com/trac/project-dtrace/browser/trunk/apache22/apr-util-hook-probes.patch
This patch (util-hook) is committed into apache already.
I was concerned that quite a few were just tracing function boundaries,
which the dtrace does already for us with out the necessity of USDT probes
baked into the code.
For e.g in APR_IMPLEMENT_XXX macros, the below are inserted.
but APR_IMPLEMENT_XXX macros already create function boundaries when
they are called and these probes effectively duplicate the
instrumentation available.
/**
* @file apr_hooks.h
* @brief Apache hook functions
@@ -107,12 +124,21 @@
ns##_LINK_##name##_t *pHook; \
int n; \
\
- if(!_hooks.link_##name) \
- return; \
+ OLD_DTRACE_PROBE(name##__entry); \
\
- pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
- for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
- pHook[n].pFunc args_use; \
+ if(_hooks.link_##name) \
+ { \
+ pHook=(ns##_LINK_##name##_t *)_hooks.link_##name->elts; \
+ for(n=0 ; n < _hooks.link_##name->nelts ; ++n) \
+ { \
+ OLD_DTRACE_PROBE1(name##__dispatch__invoke, (char
*)pHook[n].szName); \
+ pHook[n].pFunc args_use; \
+ OLD_DTRACE_PROBE2(name##__dispatch__complete, (char
*)pHook[n].szName, 0); \
+ } \
+ } \
+\
+ OLD_DTRACE_PROBE1(name##__return, 0); \
+\
}
What do you think?
rahul
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1. e4 _
