Re: 64-bit oprofile + squid

ons 2008-04-30 klockan 15:58 +0800 skrev Adrian Chadd:
> I figured out how to extract sensible callgraph oprofile reporting out of a 64 bit
> install.
>
> Notes are here:
>
> http://code.google.com/p/cacheboy/wiki/CodeProfiling
>
> Basically - it seems the "omit-frame-pointer" optimisation GCC does stops
> the inclusion of what oprofile needs to walk the callgraph.

Not too strange. Did the same for GDB for many years, and still do for
many other debuggers.

Without the framepointer you must use extended debug information in the
object to calculate the stack frame boundaries as the stack isn't self
described any more, or do what the kernel oops stack tracer do and
plain guess what may be valid code return pointers... (which often
introduces false calls from old data still remaining in the stack
memory).

Having the frame pointer do cost a little in performance however as you
get one register less for the compiler to use. But on the good side the
assembly code gets a lot easier to follow...

Regards
Henrik
Received on Wed Apr 30 2008 - 10:29:26 MDT