rcu: Event-trace markers for computing RCU CPU utilization
This commit adds the trace_rcu_utilization() marker that is to be
used to allow postprocessing scripts compute RCU's CPU utilization,
give or take event-trace overhead. Note that we do not include RCU's
dyntick-idle interface because event tracing requires RCU protection,
which is not available in dyntick-idle mode.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h
index db3f6e9..ab458eb 100644
--- a/include/trace/events/rcu.h
+++ b/include/trace/events/rcu.h
@@ -7,29 +7,58 @@
#include <linux/tracepoint.h>
/*
- * Tracepoint for calling rcu_do_batch, performed to start callback invocation:
+ * Tracepoint for start/end markers used for utilization calculations.
+ * By convention, the string is of the following forms:
+ *
+ * "Start <activity>" -- Mark the start of the specified activity,
+ * such as "context switch". Nesting is permitted.
+ * "End <activity>" -- Mark the end of the specified activity.
*/
-TRACE_EVENT(rcu_batch_start,
+TRACE_EVENT(rcu_utilization,
- TP_PROTO(long callbacks_ready, int blimit),
+ TP_PROTO(char *s),
- TP_ARGS(callbacks_ready, blimit),
+ TP_ARGS(s),
TP_STRUCT__entry(
- __field( long, callbacks_ready )
- __field( int, blimit )
+ __field(char *, s)
),
TP_fast_assign(
- __entry->callbacks_ready = callbacks_ready;
- __entry->blimit = blimit;
+ __entry->s = s;
),
- TP_printk("CBs=%ld bl=%d", __entry->callbacks_ready, __entry->blimit)
+ TP_printk("%s", __entry->s)
);
/*
- * Tracepoint for the invocation of a single RCU callback
+ * Tracepoint for marking the beginning rcu_do_batch, performed to start
+ * RCU callback invocation. The first argument is the total number of
+ * callbacks (including those that are not yet ready to be invoked),
+ * and the second argument is the current RCU-callback batch limit.
+ */
+TRACE_EVENT(rcu_batch_start,
+
+ TP_PROTO(long qlen, int blimit),
+
+ TP_ARGS(qlen, blimit),
+
+ TP_STRUCT__entry(
+ __field(long, qlen)
+ __field(int, blimit)
+ ),
+
+ TP_fast_assign(
+ __entry->qlen = qlen;
+ __entry->blimit = blimit;
+ ),
+
+ TP_printk("CBs=%ld bl=%d", __entry->qlen, __entry->blimit)
+);
+
+/*
+ * Tracepoint for the invocation of a single RCU callback function.
+ * The argument is a pointer to the RCU callback itself.
*/
TRACE_EVENT(rcu_invoke_callback,
@@ -38,20 +67,23 @@
TP_ARGS(rhp),
TP_STRUCT__entry(
- __field( void *, rhp )
- __field( void *, func )
+ __field(void *, rhp)
+ __field(void *, func)
),
TP_fast_assign(
- __entry->rhp = rhp;
- __entry->func = rhp->func;
+ __entry->rhp = rhp;
+ __entry->func = rhp->func;
),
TP_printk("rhp=%p func=%pf", __entry->rhp, __entry->func)
);
/*
- * Tracepoint for the invocation of a single RCU kfree callback
+ * Tracepoint for the invocation of a single RCU callback of the special
+ * kfree() form. The first argument is a pointer to the RCU callback
+ * and the second argument is the offset of the callback within the
+ * enclosing RCU-protected data structure.
*/
TRACE_EVENT(rcu_invoke_kfree_callback,
@@ -60,12 +92,12 @@
TP_ARGS(rhp, offset),
TP_STRUCT__entry(
- __field(void *, rhp )
- __field(unsigned long, offset )
+ __field(void *, rhp)
+ __field(unsigned long, offset)
),
TP_fast_assign(
- __entry->rhp = rhp;
+ __entry->rhp = rhp;
__entry->offset = offset;
),
@@ -73,7 +105,8 @@
);
/*
- * Tracepoint for leaving rcu_do_batch, performed after callback invocation:
+ * Tracepoint for exiting rcu_do_batch after RCU callbacks have been
+ * invoked. The first argument is the number of callbacks actually invoked.
*/
TRACE_EVENT(rcu_batch_end,
@@ -82,11 +115,11 @@
TP_ARGS(callbacks_invoked),
TP_STRUCT__entry(
- __field( int, callbacks_invoked )
+ __field(int, callbacks_invoked)
),
TP_fast_assign(
- __entry->callbacks_invoked = callbacks_invoked;
+ __entry->callbacks_invoked = callbacks_invoked;
),
TP_printk("CBs-invoked=%d", __entry->callbacks_invoked)