trace: remove global 'uint16 dstate[]' array

Instead of having a global dstate array, declare a single
'uint16 TRACE_${EVENT_NAME}_DSTATE' variable for each
trace event. Record a pointer to this variable in the
TraceEvent struct too.

By turning trace_event_get_state_dynamic_by_id into a
macro, this still hits the fast path, and cache affinity
is ensured by declaring all the uint16 vars adjacent to
each other.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 1475588159-30598-7-git-send-email-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/trace/event-internal.h b/trace/event-internal.h
index 074faf6862..4a98d09153 100644
--- a/trace/event-internal.h
+++ b/trace/event-internal.h
@@ -19,6 +19,12 @@
  * @vcpu_id: Unique per-vCPU event identifier.
  * @name: Event name.
  * @sstate: Static tracing state.
+ * @dstate: Dynamic tracing state
+ *
+ * Interpretation of @dstate depends on whether the event has the 'vcpu'
+ *  property:
+ * - false: Boolean value indicating whether the event is active.
+ * - true : Integral counting the number of vCPUs that have this event enabled.
  *
  * Opaque generic description of a tracing event.
  */
@@ -27,6 +33,7 @@ typedef struct TraceEvent {
     TraceEventVCPUID vcpu_id;
     const char * name;
     const bool sstate;
+    uint16_t *dstate;
 } TraceEvent;
 
 void trace_event_set_state_dynamic_init(TraceEvent *ev, bool state);