Hi all.
I'm running oprofile on a ppc 603 (in timer mode) and believe I'm getting reports on samples for the wrong symbol/function.
When running opreport for a specific network module (MyEth), I get a number of samples reported in a function (below: MyCos_Init) used when loading the module. This occurs for every test (iperf), although I reset the profiling data in between I do not reload the module for each run, so there should be no reason for the opreport to report samples for this function. I've also instrumented the module, to verify that i do not call the MyCos_Init repeatedly (in fact it is not called at all after I've loaded it)
The report looks like this..
>~# opreport -l -p /lib/modules/ MyEth
Overflow stats not available
CPU: CPU with timer interrupt, speed 0 MHz (estimated)
Profiling through timer interrupt
warning: could not check that the binary file /lib/modules/MyEth has not been modified since the profile was taken. Results may be inaccurate.
samples % symbol name
228 39.3782 MyEth_TxThread
219 37.8238 MyEth_TxDone
83 14.3351 MyCos_Init
49 8.4629 MyEth_start_xmit
Looking at a more detailed report (with "-d" option in opreport), I see where the samples for the function MyCos_Init are taken (from address 230c to 238c). MyCos_Init is located at 1e3c.
00001e3c 83 14.3351 MyCos_Init
0000230c 9 10.8434
00002318 5 6.0241
0000231c 1 1.2048
00002324 9 10.8434
00002338 21 25.3012
0000233c 2 2.4096
00002344 10 12.0482
0000237c 14 16.8675
00002384 10 12.0482
0000238c 2 2.4096
Running "nm -n /lib/modules/MyEth" to list symbols (sorted), I find the MyCos_Init at the bottom of the list (Last function / higest address). Is Oprofile just
reporting defaulting to the last symbol if it can find any reasonable symbol/function?
If I then look in "/proc/kallsyms" I find where the function is located, and see there are functions below it belonging to my module. The
list shows me that the function MyCos_Init takes 3E8 address..
c9088e3c t MyCos_Init [MyEth]
c9089224 t MyEth_p_cleanup [MyEth]
c90892a4 t MyEth_exit [MyEth]
c90892a4 t cleanup_module [MyEth]
c9089e58 r __func__.0 [MyEth]
c9089e60 r __func__.1 [MyEth]
Then finally. Adding 3E8 (size allocated for function in kernel) to the address found from "opreport" /"nm" for the MyCos_Init function ( 0x00001e3c) I get 0x00002224.
So the reported samples from opreport is after the addresses for this function. So is oprofile reporting samples for a wrong function or what? Or I'm I doing something wrong?
Thanks for any assistance.
Best Regards
Preben