Use user-provided irq count for TS_SYSCALL_IN_END

To detect interrupts that interfered after the initial time stamp was
recorded, this patch changes sched_trace to also record the IRQ count
as observed by userspace.

3 files changed, 47 insertions, 1 deletions

diff --git a/include/litmus/litmus.h b/include/litmus/litmus.h
index f7893ef18162..1cb3eaf25740 100644
--- a/include/litmus/litmus.h
+++ b/include/litmus/litmus.h
@@ -270,9 +270,28 @@ static inline int has_control_page(struct task_struct* t)
 }
 
 
+#ifdef CONFIG_SCHED_OVERHEAD_TRACE
+
 #define TS_SYSCALL_IN_START                                             \
         if (has_control_page(current)) {                                \
                 __TS_SYSCALL_IN_START(&get_control_page(current)->ts_syscall_start); \
         }
 
+#define TS_SYSCALL_IN_END                                               \
+        if (has_control_page(current)) {                                \
+                uint64_t irqs;                                          \
+                local_irq_disable();                                    \
+                irqs = get_control_page(current)->irq_count -           \
+                        get_control_page(current)->irq_syscall_start;   \
+                __TS_SYSCALL_IN_END(&irqs);                             \
+                local_irq_enable();                                     \
+        }
+
+#else
+
+#define TS_SYSCALL_IN_START
+#define TS_SYSCALL_IN_END
+
+#endif
+
 #endif
diff --git a/include/litmus/trace.h b/include/litmus/trace.h
index ee55c2eca482..635dd8986bd4 100644
--- a/include/litmus/trace.h
+++ b/include/litmus/trace.h
@@ -34,6 +34,7 @@ feather_callback void save_timestamp_task(unsigned long event, unsigned long t_p
 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);
 
 #define TIMESTAMP(id) ft_event0(id, save_timestamp)
 
@@ -53,6 +54,9 @@ feather_callback void save_timestamp_time(unsigned long event, unsigned long tim
 #define TIMESTAMP_TIME(id, time_ptr) \
         ft_event1(id, save_timestamp_time, (unsigned long) time_ptr)
 
+#define TIMESTAMP_IRQ(id, irq_count_ptr) \
+        ft_event1(id, save_timestamp_irq, (unsigned long) irq_count_ptr)
+
 #else /* !CONFIG_SCHED_OVERHEAD_TRACE */
 
 #define TIMESTAMP(id)        /* no tracing */
@@ -69,6 +73,8 @@ feather_callback void save_timestamp_time(unsigned long event, unsigned long tim
 
 #define TIMESTAMP_TIME(id, time_ptr) /* no tracing */
 
+#define TIMESTAMP_IRQ(id, irq_count_ptr) /* no tracing */
+
 #endif
 
 
@@ -81,7 +87,7 @@ feather_callback void save_timestamp_time(unsigned long event, unsigned long tim
  */
 
 #define __TS_SYSCALL_IN_START(p)        TIMESTAMP_TIME(10, p)
-#define TS_SYSCALL_IN_END               TIMESTAMP_CUR(11)
+#define __TS_SYSCALL_IN_END(p)          TIMESTAMP_IRQ(11, p)
 
 #define TS_SYSCALL_OUT_START            TIMESTAMP_CUR(20)
 #define TS_SYSCALL_OUT_END              TIMESTAMP_CUR(21)
diff --git a/litmus/trace.c b/litmus/trace.c
index c511003ea911..45cd662c021d 100644
--- a/litmus/trace.c
+++ b/litmus/trace.c
@@ -166,6 +166,27 @@ void save_timestamp_time(unsigned long event,
         }
 }
 
+/* Record user-reported IRQ count */
+void save_timestamp_irq(unsigned long event,
+                        unsigned long irq_counter_ptr)
+{
+        uint64_t* irqs = (uint64_t*) irq_counter_ptr;
+        unsigned int seq_no;
+        struct timestamp *ts;
+        seq_no = fetch_and_inc((int *) &ts_seq_no);
+        if (ft_buffer_start_write(trace_ts_buf, (void**)  &ts)) {
+                ts->event     = event;
+                ts->seq_no    = seq_no;
+                ts->pid       = current->pid;
+                ts->cpu       = raw_smp_processor_id();
+                ts->task_type = is_realtime(current) ? TSK_RT : TSK_BE;
+                ts->irq_count = *irqs;
+                ts->irq_flag  = *irqs > 0;
+                ts->timestamp = ft_timestamp();
+                ft_buffer_finish_write(trace_ts_buf, ts);
+        }
+}
+
 /******************************************************************************/
 /*                        DEVICE FILE DRIVER                                  */
 /******************************************************************************/