Messages in this thread | | | Date | Tue, 21 Nov 2006 19:26:02 +0300 | From | Sergei Shtylyov <> | Subject | Re: LTTng do_page_fault vs handle_mm_fault instrumentation |
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Hello.
Mathieu Desnoyers wrote:
> I would like to discuss your suggestion of moving the do_page_fault > instrumentation to handle_mm_fault. On one side, it helps removing architecture > dependant instrumentation, but on the other hand :
> 1- We cannot access the struct pt_regs in all cases (there may be an invalid > current task struct). > 2- We cannot distinguish between calls to handle_mm_fault from the page fault > handler or from get_user_pages. > 3- Some people complain about not having enough information about the cause of > the page fault (see the forward below). > > So instead of staying between my users who ask for those feature and kernel > developers who wish to reduce the intrusiveness of instrumentation (which is a > nice goal : moving the syscall entry/exit instrumentation do do_syscall_trace > has helped simplifying the instrumentation), I prefer to open the discussion > about it.
It seems I've missed the whole story behind this move. For me, it was more a question of consistency: if we're trying to trace all trap handlers, why not page fault one? So, I just wanted my old LTT tracepoints back. :-)
> Ideas/comments are welcome.
> Regards,
> Mathieu
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