Re: [PATCH 1/2] Fix perf LBR filtering

From: Andi Kleen
Date: Fri Apr 26 2013 - 15:46:42 EST

> OK, so how about we use something like:
> is_kernel_text() || is_module_text_address()

is_module_text_address() has to walk all modules.
A random system with a distro kernel I checked has 101 modules loaded.

16 * 101 = too much

I don't think you want to spend that many cycles in the NMI
handler for a dubious feature. Ok in theory you could
add something with binary search, but that would be quite
a bit of effort and it would be probably challenging
to do that all NMI safe.

Also it wouldn't work for all these new kernel JITs people
are doing of course.

Still think my patch is the best so far? (plus the missing
root check)

ak@xxxxxxxxxxxxxxx -- Speaking for myself only.
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