Feather-Trace: add support for latency tracing/

This patch adds support for tracing release latency in LITMUS^RT.

2 files changed, 19 insertions, 0 deletions

diff --git a/include/litmus/trace.h b/include/litmus/trace.h
index 489b3d84f880..8ad4966c602e 100644
--- a/include/litmus/trace.h
+++ b/include/litmus/trace.h
@@ -32,6 +32,7 @@ feather_callback void save_timestamp(unsigned long event);
 feather_callback void save_timestamp_def(unsigned long event, unsigned long type);
 feather_callback void save_timestamp_task(unsigned long event, unsigned long t_ptr);
 feather_callback void save_timestamp_cpu(unsigned long event, unsigned long cpu);
+feather_callback void save_task_latency(unsigned long event, unsigned long when_ptr);
 feather_callback void save_timestamp_time(unsigned long event, unsigned long time_ptr);
 feather_callback void save_timestamp_irq(unsigned long event, unsigned long irq_count_ptr);
 feather_callback void save_timestamp_hide_irq(unsigned long event);
@@ -48,6 +49,9 @@ feather_callback void save_timestamp_hide_irq(unsigned long event);
 #define CTIMESTAMP(id, cpu) \
         ft_event1(id, save_timestamp_cpu, (unsigned long) cpu)
 
+#define LTIMESTAMP(id, task) \
+        ft_event1(id, save_task_latency, (unsigned long) task)
+
 #define TIMESTAMP_TIME(id, time_ptr) \
         ft_event1(id, save_timestamp_time, (unsigned long) time_ptr)
 
@@ -69,6 +73,8 @@ feather_callback void save_timestamp_hide_irq(unsigned long event);
 
 #define CTIMESTAMP(id, cpu)  /* no tracing */
 
+#define LTIMESTAMP(id, when_ptr) /* no tracing */
+
 #define TIMESTAMP_TIME(id, time_ptr) /* no tracing */
 
 #define TIMESTAMP_IRQ(id, irq_count_ptr) /* no tracing */
@@ -134,4 +140,6 @@ feather_callback void save_timestamp_hide_irq(unsigned long event);
 #define TS_SEND_RESCHED_START(c)        CTIMESTAMP(190, c)
 #define TS_SEND_RESCHED_END             TIMESTAMP_IN_IRQ(191)
 
+#define TS_RELEASE_LATENCY(when)        LTIMESTAMP(208, &(when))
+
 #endif /* !_SYS_TRACE_H_ */
diff --git a/litmus/trace.c b/litmus/trace.c
index 7e4df5f0e12a..790686b1322c 100644
--- a/litmus/trace.c
+++ b/litmus/trace.c
@@ -155,6 +155,17 @@ feather_callback void save_timestamp_cpu(unsigned long event,
                         0, 1);
 }
 
+feather_callback void save_task_latency(unsigned long event,
+                                        unsigned long when_ptr)
+{
+        lt_t now = litmus_clock();
+        lt_t *when = (lt_t*) when_ptr;
+
+        write_timestamp(event, TSK_RT, raw_smp_processor_id(), 0,
+                        0, 1, 0,
+                        now - *when, 0);
+}
+
 /* fake timestamp to user-reported time */
 feather_callback void save_timestamp_time(unsigned long event,
                          unsigned long ptr)