Feather-Trace: add LITMUS^RT overhead tracing infrastructure

This patch adds the main infrastructure for tracing overheads in
LITMUS^RT.  It does not yet introduce any tracepoints into the kernel.

1 files changed, 25 insertions, 0 deletions

diff --git a/litmus/Kconfig b/litmus/Kconfig
index 7456eb209cf7..0c7e06b922a1 100644
--- a/litmus/Kconfig
+++ b/litmus/Kconfig
@@ -24,6 +24,31 @@ config FEATHER_TRACE
           you still need to enable SCHED_TASK_TRACE and/or SCHED_OVERHEAD_TRACE to
           actually enable any events.
 
+config SCHED_OVERHEAD_TRACE
+        bool "Record timestamps for overhead measurements"
+        depends on FEATHER_TRACE
+        default y
+        help
+          Export event stream for overhead tracing.
+          Say Yes for overhead tracing.
+
+config SCHED_OVERHEAD_TRACE_SHIFT
+       int "Buffer size for Feather-Trace overhead data"
+       depends on SCHED_OVERHEAD_TRACE
+       range 15 32
+       default 22
+       help
+
+         Select the buffer size for the Feather-Trace overhead tracing
+         infrastructure (/dev/litmus/ft_trace0 & ftcat) as a power of two.  The
+         larger the buffer, the less likely the chance of buffer overflows if
+         the ftcat process is starved by real-time activity. In machines with
+         large memories, large buffer sizes are recommended.
+
+         Examples: 16 =>   2 MB
+                   24 => 512 MB
+                   26 =>  2G MB
+
 endmenu
 
 endmenu