Hi I want to use/read the PMU counters for 'instructions' and 'cycles', from within the kernel, to measure the overhead of different in-kernel functions (and calc the pipeline efficiency ala perf-stat insns per cycle).
What is the prefered way/API to read these counters, without conflicting with the perf tool? I've already looked at Andi Kleens "simple-pmu" kernel module https://github.com/andikleen/simple-pmu/ Thus, I have figured out how I can hack this together open-coded. I'm looking for advice on howto use the existing perf APIs ? I basically just need a in-kernel API to turn in these counters, and then I can just read them via the rdpcm instruction. Info I already learned (correct me if I'm wrong): The 'instructions' counter is the "Instruction Retired" counter * Event num: 0xC0, Umask: 0x00 * Read via rdpmc 0x40000000 The 'cycles' counter is the "Unhalted core cycles" counter * Event num: 0x3C, Umask: 0x00 * Read via rdpmc 0x40000001 I'm uncertain about the rdpmc hex values (taken from simple-pmu). -- Best regards, Jesper Dangaard Brouer MSc.CS, Sr. Network Kernel Developer at Red Hat Author of http://www.iptv-analyzer.org LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
