u64 tstamp_running;
u64 tstamp_stopped;
+ /*
+ * timestamp shadows the actual context timing but it can
+ * be safely used in NMI interrupt context. It reflects the
+ * context time as it was when the event was last scheduled in.
+ *
+ * ctx_time already accounts for ctx->timestamp. Therefore to
+ * compute ctx_time for a sample, simply add perf_clock().
+ */
+ u64 shadow_ctx_time;
+
struct perf_event_attr attr;
struct hw_perf_event hw;