tracing: Combine event filter_active and enable into single flags field
The filter_active and enable both use an int (4 bytes each) to
set a single flag. We can save 4 bytes per event by combining the
two into a single integer.
text data bss dec hex filename
4913961 1088356 861512 6863829 68bbd5 vmlinux.orig
4894944 1018052 861512 6774508 675eec vmlinux.id
4894871 1012292 861512 6768675 674823 vmlinux.flags
This gives us another 5K in savings.
The modification of both the enable and filter fields are done
under the event_mutex, so it is still safe to combine the two.
Note: Although Mathieu gave his Acked-by, he would like it documented
that the reads of flags are not protected by the mutex. The way the
code works, these reads will not break anything, but will have a
residual effect. Since this behavior is the same even before this
patch, describing this situation is left to another patch, as this
patch does not change the behavior, but just brought it to Mathieu's
attention.
v2: Updated the event trace self test to for this change.
Acked-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 0be0285..5ac97a4 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -143,6 +143,16 @@
int (*raw_init)(struct ftrace_event_call *);
};
+enum {
+ TRACE_EVENT_FL_ENABLED_BIT,
+ TRACE_EVENT_FL_FILTERED_BIT,
+};
+
+enum {
+ TRACE_EVENT_FL_ENABLED = (1 << TRACE_EVENT_FL_ENABLED_BIT),
+ TRACE_EVENT_FL_FILTERED = (1 << TRACE_EVENT_FL_FILTERED_BIT),
+};
+
struct ftrace_event_call {
struct list_head list;
struct ftrace_event_class *class;
@@ -154,8 +164,15 @@
void *mod;
void *data;
- int enabled;
- int filter_active;
+ /*
+ * 32 bit flags:
+ * bit 1: enabled
+ * bit 2: filter_active
+ *
+ * Must hold event_mutex to change.
+ */
+ unsigned int flags;
+
int perf_refcount;
};