Confusing output from Kcachegrind.

Attachment 11072

Hi,
I am profiling my code with Kcachegrind. But I am confused with the output tree-map view of the call graph (attached).

1. Above the main() function, u will see a "below main()" and 0x08049140 functions. What r these?

2. In the lower part of the tree, u will also see a lot of functions with hexadecimal numbers instead of names. Why is this?

3. Are these hexadecimal numbers absolute addresses (i.e. not offset) of the code section of these functions? or not?

4. Do these hexadecimal numbers have something to do with "debugging information"?

Bye.

Well the OS doesn't just load your program image and jump to main.

Normally, the program starts at a symbol called _start, which will do some stuff before calling into the clib startup routine. This in turn eventually calls main.

You should probably compile with "-g" flag to get more symbol information. Functions declared static for example might only show as hex addresses otherwise.

> 3. Are these hexadecimal numbers absolute addresses (i.e. not offset) of the code section of these functions? or not?
They will be "absolute" within the virtual address space assigned to the process.

> 4. Do these hexadecimal numbers have something to do with "debugging information"?
Add the debug flag to the compile and link steps.

Quote:

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Originally Posted by Salem

Well the OS doesn't just load your program image and jump to main.

Normally, the program starts at a symbol called _start, which will do some stuff before calling into the clib startup routine. This in turn eventually calls main.

You should probably compile with "-g" flag to get more symbol information. Functions declared static for example might only show as hex addresses otherwise.

> 3. Are these hexadecimal numbers absolute addresses (i.e. not offset) of the code section of these functions? or not?
They will be "absolute" within the virtual address space assigned to the process.

> 4. Do these hexadecimal numbers have something to do with "debugging information"?
Add the debug flag to the compile and link steps.

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Hi, I have compiled the code with -g option (in Ubuntu 10.10) to generate this output.

If you do "nm myprog", (read the man page for nm for lots of interesting options), you should get a nice list of function names and addresses.

Are the addresses reported by the tools the actual start addresses of functions, or do they correspond to some small offset from the true start of the function?