On Thu, 23 Apr 2015, Steven Rostedt wrote: > This is the port of the hardware latency detector from the -rt patch > to mainline. Instead of keeping it as a device that had its own debugfs > filesystem infrastructure, it made more sense to make it into a tracer > like irqsoff and wakeup latency tracers currently are. > > With this patch set, a new tracer is enabled if CONFIG_HWLAT_TRACER is > enabled. Inside the available_tracers file will be hwlat_detector. > > # cd /sys/kernel/debug/tracing > # echo hwlat_detector > current_tracer > > will enable the hwlat_detector that will create per cpu kernel threads > (which cpus is defined by the tracing/hwlat_detector/cpumask, default > is just CPU 0). > > Like the other tracers (function, function_graph, preemptirqsoff, > and mmiotracer), the hwlat_detector can add a significant performance > penalty when enabled. As each of the threads created will go into a spin > checking the trace_local_clock (sched_clock) for any gaps of time > and will report them if they are greater than the threshold defined > by tracing/tracing_thresh (usecs, default 10). The spin is performed with > interrupts disabled and runs for "width" usecs in "window" usecs time. The That's fine, but this still lacks a detection of NMI disturbance. We've seen false positives reported over and over when stuff like the NMI watchdog or perf was enabled while running this. Aside of that isn't there a way to detect SMI crap with performance counters on recent hardware? Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
