Em Thu, Aug 06, 2015 at 03:44:53PM -0400, [email protected] escreveu: > From: Kan Liang <[email protected]> > Here are some examples and test results. > > 1. Comparing the elapsed time and perf.data size from "kernbench -M -H". > > The test command for FULL callgraph and time support. > "perf record -e > '{cpu/cpu-cycles,period=100000/,cpu/instructions,period=20000/p}' > --call-graph fp --time"
Jiri, while testing this I noticed that the message for EINVAL when using the cpu// syntax (per-event settings) is cryptic: [root@zoo ~]# perf record -e 'cpu/cpu-cycles,call-graph=fp,time,period=100000/p' ls Error: The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu/cpu-cycles,call-graph=fp,time,period=100000/p). /bin/dmesg may provide additional information. No CONFIG_PERF_EVENTS=y kernel support configured? Whereas if we use -F, it is much, much clearer, telling the user exactly what is failing and what needs to be done to make it work: [root@zoo ~]# perf record -F 100000 -e cpu/cpu-cycles/ usleep 1 Maximum frequency rate (25000) reached. Please use -F freq option with lower value or consider tweaking /proc/sys/kernel/perf_event_max_sample_rate. [root@zoo ~]# Hope this is something easy to wire up, given your event parsing kung foo skillz... ;-) - Arnaldo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
