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whatis 'limited feature mode' in discover?

Hi,

I was playing with discover from Studio 12 update 4, and found the performance of instrumented binaries really slow (factor of 50 - 60 slower than uninstrumented binaries). With -l, the performance is far better, but I wonder what these 'limited features' really mean. The documentation does not expand on this. Could someone explain the tradeoff between 'normal instrumentation' and 'limited feature mode' (i.e. which checks are done/omitted in these modes)?

Regards

Dieter Ruppert

Best Answer

  • Darryl Gove-Oracle
    Darryl Gove-Oracle Member Posts: 82
    edited Feb 25, 2015 12:52PM Accepted Answer

    Full instrumentation means taking the binaries apart and checking (nearly) every memory operation to see if it's valid or not. So the slowdown is proportional to the number of memory operations, so some apps will be impacted more than others. With light instrumentation the tool is just checking the library calls, and not instrumenting the binary. So you can pick up some things - like memory that wasn't freed, or double free - but you cannot get anywhere near the level of detail from as from full instrumentation. You might find this blog post from Raj interesting: https://blogs.oracle.com/raj/entry/move_over_purify_and_valgrind He talks about the slowdown from instrumentation. Regards, Darryl.

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