Messages in this thread | | | Date | Wed, 20 Sep 2006 14:25:41 -0400 | From | Karim Yaghmour <> | Subject | Re: [PATCH] Linux Kernel Markers |
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Hello Frank,
Frank Ch. Eigler wrote: > My interpretation of Martin's Monday proposal is that, if implemented, > we wouldn't need any of this nop/int3 stuff. If function being > instrumented were recompiled on-the-fly, then it could sport plain & > direct C-level calls to the instrumentation handlers.
Absolutely. I guess the length of these threads is just fertile ground for misunderstandings. Basically what Hiramatsu-san and myself were discussing was just the mechanism for selecting/ forking in between the uninstrumented function and the instrumented one.
So, to recap:
If you had 100,000 instrumentation points in the scheduler (obviously a totally bogus number here ...) you'd have 2 functions: 1- one with no instrumentation at all, but with a 5byte filler such as the one presented by Hiramatsu-san. 2- one with the instrumentation.
Early in the proposal, the mechanics of switching in between "1" and "2" seemed to be problematic, but I think with Hiramatsu-san's proposal and, on the x86, djprobes, we've got it figured out.
Let me know if I'm not providing enough detail.
Thanks,
Karim
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