Merge remote-tracking branch 'ftrace/for-next'

[deliverable/linux.git] / kernel / trace / Kconfig

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f4b86e8ca1e77dba8d969aa009491876186f457f..2a96b063d6590f326410feaa55fbb7f817241c0c 100644 (file)
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -24,11 +24,6 @@ config HAVE_FUNCTION_GRAPH_TRACER
        help
          See Documentation/trace/ftrace-design.txt
 
-config HAVE_FUNCTION_GRAPH_FP_TEST
-       bool
-       help
-         See Documentation/trace/ftrace-design.txt
-
 config HAVE_DYNAMIC_FTRACE
        bool
        help
@@ -221,6 +216,41 @@ 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