On Thu, 3 Sep 2015, Dennis Gnad wrote: > In the meantime I got some information for the x86 architecture. There, the > performance counters can be read directly in userspace by the interface over > MSR's similar to readmsr/msrtool, where a reliable interval of <10ms can be > achieved. [1]
this is probably getting a bit off topic for linux-perf-users, but yes, I was doing similar work recently. I was trying to validate the RAPL values (which are only estimates, not actual sensor results, on most CPUs). This involved trying to read the RAPL and perf counters at a high rate of speed. And yes, it seems that reading the MSRs directly from userspace has a lot less overhead than trying to use the perf_event sampling interface. I had hoped that having an in-kernel ring buffer would be faster than just manually dumping the results to disk continually from userspace, but maybe NMI overhead is just too high. Vince -- 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
