diff options
Diffstat (limited to 'kernel/trace/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index f4b86e8ca1e7..72c07c2ffd79 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -221,6 +221,41 @@ config SCHED_TRACER This tracer tracks the latency of the highest priority task to be scheduled in, starting from the point it has woken up. +config HWLAT_TRACER + bool "Tracer to detect hardware latencies (like SMIs)" + select GENERIC_TRACER + help + This tracer, when enabled will create one or more kernel threads, + depening on what the cpumask file is set to, which each thread + spinning in a loop looking for interruptions caused by + something other than the kernel. For example, if a + System Management Interrupt (SMI) takes a noticeable amount of + time, this tracer will detect it. This is useful for testing + if a system is reliable for Real Time tasks. + + Some files are created in the tracing directory when this + is enabled: + + hwlat_detector/width - time in usecs for how long to spin for + hwlat_detector/window - time in usecs between the start of each + iteration + + A kernel thread is created that will spin with interrupts disabled + for "width" microseconds in every "widow" cycle. It will not spin + for "window - width" microseconds, where the system can + continue to operate. + + The output will appear in the trace and trace_pipe files. + + When the tracer is not running, it has no affect on the system, + but when it is running, it can cause the system to be + periodically non responsive. Do not run this tracer on a + production system. + + To enable this tracer, echo in "hwlat" into the current_tracer + file. Every time a latency is greater than tracing_thresh, it will + be recorded into the ring buffer. + config ENABLE_DEFAULT_TRACERS bool "Trace process context switches and events" depends on !GENERIC_TRACER |