Feather-Trace: keep track of interrupt-related interference.

Increment a processor-local counter whenever an interrupt is handled.
This allows Feather-Trace to include a (truncated) counter and a flag
to report interference from interrupts. This could be used to filter
samples that were disturbed by interrupts.

2 files changed, 24 insertions, 1 deletions

diff --git a/include/litmus/trace.h b/include/litmus/trace.h
index e2926a08c2f..e809376d648 100644
--- a/include/litmus/trace.h
+++ b/include/litmus/trace.h
@@ -20,7 +20,9 @@ struct timestamp {
         uint32_t                seq_no;
         uint8_t                 cpu;
         uint8_t                 event;
-        uint8_t                 task_type;
+        uint8_t                 task_type:2;
+        uint8_t                 irq_flag:1;
+        uint8_t                 irq_count:5;
 };
 
 /* tracing callbacks */
diff --git a/include/litmus/trace_irq.h b/include/litmus/trace_irq.h
new file mode 100644
index 00000000000..f18b127a089
--- /dev/null
+++ b/include/litmus/trace_irq.h
@@ -0,0 +1,21 @@
+#ifndef _LITMUS_TRACE_IRQ_H_
+#define _LITMUS_TRACE_IRQ_H_
+
+#ifdef CONFIG_SCHED_OVERHEAD_TRACE
+
+extern DEFINE_PER_CPU(atomic_t, irq_fired_count);
+
+static inline void ft_irq_fired(void)
+{
+        /* Only called with preemptions disabled.  */
+        atomic_inc(&__get_cpu_var(irq_fired_count));
+}
+
+
+#else
+
+#define ft_irq_fired() /* nothing to do */
+
+#endif
+
+#endif