Messages in this thread | | | Date | Tue, 19 Sep 2006 12:24:18 -0700 | From | Martin Bligh <> | Subject | Re: [PATCH] Linux Kernel Markers |
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Mathieu Desnoyers wrote: > * Vara Prasad (prasadav@us.ibm.com) wrote: > >>Martin Bligh wrote: >> >> >>>[...] >>>Depends what we're trying to fix. I was trying to fix two things: >>> >>>1. Flexibility - kprobes seem unable to access all local variables etc >>>easily, and go anywhere inside the function. Plus keeping low overhead >>>for doing things like keeping counters in a function (see previous >>>example I mentioned for counting pages in shrink_list). >>> >> >>Using tools like systemtap on can consult DWARF information and put >>probes in the middle of the function and access local variables as well, >>that is not the real problem. The issue here is compiler doesn't seem to >>generate required DWARF information in some cases due to optimizations. >>The other related problem is when there exists debug information, the >>way to specify the breakpoint location is using line number which is not >>maintainable, having a marker solves this problem as well. Your proposal >>still doesn't solve the need for markers if i understood correctly. > > His implementation makes a heavy use of a marker mechanism : this is exactly > what permits to create the instrumented objects from the same source code, but > with different #defines.
I don't think it ties us to markers, though I think they're superior for maintaintance, personally. It could equally well be an out of tree normal flat patch with all the tracing in, which would make Andrew happy, even if I think it sucks ;-)
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