06-25-2009 03:56 AM
I assume netif_rx() is a Linux kernel function. Then with the SystemTap tool (http://sourceware.org/systemtap/wiki) you can insert your time measuring codeinto netif_rxon a live running system without the need to stop, rebootor recompile the kernel.
However, simpler methods might exist for your task and my method is an overkill.
06-28-2009 11:17 AM
Alternatively to what Roman suggested, you might also have a look at oprofile, which let's you profile the Linux kernel with sampling. However, this usually requires a reboot and you may also want a kernel with debug information.
06-28-2009 07:05 PM
Also VTune Performance Analyzer's sampling collector can captureperformance data for all active modules in the system. In Processes report, select vmlinuz-2.6.xx-x anddrill down all modules which has samples captured - if you want to see hotfunctions in any module, the tool will ask you vmlinuz's location and its corresponding system file (usually that is like as System.map-2.6.xx-x)