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rcu: Add event-tracing for RCU callback invocation

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There was recently some controversy about the overhead of invoking RCU
callbacks.  Add TRACE_EVENT()s to obtain fine-grained timings for the
start and stop of a batch of callbacks and also for each callback invoked.

Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
This commit is contained in:
Paul E. McKenney
2011-06-17 15:53:19 -07:00
committed by Paul E. McKenney
parent 9d68197c05
commit 29c00b4a1d
6 changed files with 219 additions and 54 deletions
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98
include/trace/events/rcu.h Normal file
View File

@@ -0,0 +1,98 @@
#undef TRACE_SYSTEM
#define TRACE_SYSTEM rcu
#if !defined(_TRACE_RCU_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_RCU_H
#include <linux/tracepoint.h>
/*
* Tracepoint for calling rcu_do_batch, performed to start callback invocation:
*/
TRACE_EVENT(rcu_batch_start,
TP_PROTO(long callbacks_ready, int blimit),
TP_ARGS(callbacks_ready, blimit),
TP_STRUCT__entry(
__field( long, callbacks_ready )
__field( int, blimit )
),
TP_fast_assign(
__entry->callbacks_ready = callbacks_ready;
__entry->blimit = blimit;
),
TP_printk("CBs=%ld bl=%d", __entry->callbacks_ready, __entry->blimit)
);
/*
* Tracepoint for the invocation of a single RCU callback
*/
TRACE_EVENT(rcu_invoke_callback,
TP_PROTO(struct rcu_head *rhp),
TP_ARGS(rhp),
TP_STRUCT__entry(
__field( void *, rhp )
__field( void *, func )
),
TP_fast_assign(
__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
*/
TRACE_EVENT(rcu_invoke_kfree_callback,
TP_PROTO(struct rcu_head *rhp, unsigned long offset),
TP_ARGS(rhp, offset),
TP_STRUCT__entry(
__field(void *, rhp )
__field(unsigned long, offset )
),
TP_fast_assign(
__entry->rhp = rhp;
__entry->offset = offset;
),
TP_printk("rhp=%p func=%ld", __entry->rhp, __entry->offset)
);
/*
* Tracepoint for leaving rcu_do_batch, performed after callback invocation:
*/
TRACE_EVENT(rcu_batch_end,
TP_PROTO(int callbacks_invoked),
TP_ARGS(callbacks_invoked),
TP_STRUCT__entry(
__field( int, callbacks_invoked )
),
TP_fast_assign(
__entry->callbacks_invoked = callbacks_invoked;
),
TP_printk("CBs-invoked=%d", __entry->callbacks_invoked)
);
#endif /* _TRACE_RCU_H */
/* This part must be outside protection */
#include <trace/define_trace.h>