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    SubjectRe: [PATCH] Linux Kernel Markers
    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 ;-)

    M.
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