1 files changed, 6 insertions, 0 deletions

diff --git a/include/litmus/rt_param.h b/include/litmus/rt_param.h
index fac939dbd33a..6456ed04fddb 100644
--- a/include/litmus/rt_param.h
+++ b/include/litmus/rt_param.h
@@ -89,8 +89,14 @@ union np_flag {
  * determining preemption/migration overheads).
  */
 struct control_page {
+        /* This flag is used by userspace to communicate non-preempive
+         * sections. */
         volatile union np_flag sched;
 
+        /* Locking overhead tracing: userspace records here the time stamp
+         * prior to starting the system call. */
+        uint64_t ts_syscall_start; /* Feather-Trace cycles */
+
         /* to be extended */
 };