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Re: [RFC]-Approaches to user space probes
anil.s.keshavamurthy wrote:
> [...]
> Sure, their is some advantange in 4, but the thing we need to see
> is whether this apporach suits probing different kinds of
> application(mainly java apps).
Could you explain why you think Java would be harder to instrument
with kernel-space probes? We may opt to compose user-kprobes along
the lines of #4, and static instrumentation (a libmudflap.so
containing hooks for language interpreters to hook up to and pass
event parameters).
> > probe user.module("/lib/libc.so.6").function("strlen") {
> > in_strlen[tid()] = 1
> Setting a variable in function entry probe and
> later trying to reset in the function return probe
> is very problematic.
> [...]
> > probe user.module("/lib/libc.so.6").function("strlen").return {
> > delete in_strlen[tid()]
> [...] in_strlen[tid()] will never gets reset and the pagefault
> count will have wrong value.
That is not such a big problem. Should such an unfortunate timing
glitch occur, the system would report a missed probe. The user could
then try again.
- FChE