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Subject[tip: locking/core] locking: Add lock contention tracepoints
The following commit has been merged into the locking/core branch of tip:

Commit-ID: 16edd9b511a13e7760ed4b92ba4e39bacda5c86f
Gitweb: https://git.kernel.org/tip/16edd9b511a13e7760ed4b92ba4e39bacda5c86f
Author: Namhyung Kim <namhyung@kernel.org>
AuthorDate: Tue, 22 Mar 2022 11:57:08 -07:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 05 Apr 2022 10:24:35 +02:00

locking: Add lock contention tracepoints

This adds two new lock contention tracepoints like below:

* lock:contention_begin
* lock:contention_end

The lock:contention_begin takes a flags argument to classify locks. I
found it useful to identify what kind of locks it's tracing like if
it's spinning or sleeping, reader-writer lock, real-time, and per-cpu.

Move tracepoint definitions into mutex.c so that we can use them
without lockdep.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Link: https://lkml.kernel.org/r/20220322185709.141236-2-namhyung@kernel.org
---
include/trace/events/lock.h | 61 ++++++++++++++++++++++++++++++++++--
kernel/locking/lockdep.c | 1 +-
kernel/locking/mutex.c | 3 ++-
3 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/include/trace/events/lock.h b/include/trace/events/lock.h
index d751212..b9b6e3e 100644
--- a/include/trace/events/lock.h
+++ b/include/trace/events/lock.h
@@ -5,11 +5,21 @@
#if !defined(_TRACE_LOCK_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_LOCK_H

-#include <linux/lockdep.h>
+#include <linux/sched.h>
#include <linux/tracepoint.h>

+/* flags for lock:contention_begin */
+#define LCB_F_SPIN (1U << 0)
+#define LCB_F_READ (1U << 1)
+#define LCB_F_WRITE (1U << 2)
+#define LCB_F_RT (1U << 3)
+#define LCB_F_PERCPU (1U << 4)
+
+
#ifdef CONFIG_LOCKDEP

+#include <linux/lockdep.h>
+
TRACE_EVENT(lock_acquire,

TP_PROTO(struct lockdep_map *lock, unsigned int subclass,
@@ -78,8 +88,53 @@ DEFINE_EVENT(lock, lock_acquired,
TP_ARGS(lock, ip)
);

-#endif
-#endif
+#endif /* CONFIG_LOCK_STAT */
+#endif /* CONFIG_LOCKDEP */
+
+TRACE_EVENT(contention_begin,
+
+ TP_PROTO(void *lock, unsigned int flags),
+
+ TP_ARGS(lock, flags),
+
+ TP_STRUCT__entry(
+ __field(void *, lock_addr)
+ __field(unsigned int, flags)
+ ),
+
+ TP_fast_assign(
+ __entry->lock_addr = lock;
+ __entry->flags = flags;
+ ),
+
+ TP_printk("%p (flags=%s)", __entry->lock_addr,
+ __print_flags(__entry->flags, "|",
+ { LCB_F_SPIN, "SPIN" },
+ { LCB_F_READ, "READ" },
+ { LCB_F_WRITE, "WRITE" },
+ { LCB_F_RT, "RT" },
+ { LCB_F_PERCPU, "PERCPU" }
+ ))
+);
+
+TRACE_EVENT(contention_end,
+
+ TP_PROTO(void *lock, int ret),
+
+ TP_ARGS(lock, ret),
+
+ TP_STRUCT__entry(
+ __field(void *, lock_addr)
+ __field(int, ret)
+ ),
+
+ TP_fast_assign(
+ __entry->lock_addr = lock;
+ __entry->ret = ret;
+ ),
+
+ TP_printk("%p (ret=%d)", __entry->lock_addr, __entry->ret)
+);

#endif /* _TRACE_LOCK_H */

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 3cbd492..a6e671b 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -60,7 +60,6 @@

#include "lockdep_internals.h"

-#define CREATE_TRACE_POINTS
#include <trace/events/lock.h>

#ifdef CONFIG_PROVE_LOCKING
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 5e35859..ee2fd76 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -30,6 +30,9 @@
#include <linux/debug_locks.h>
#include <linux/osq_lock.h>

+#define CREATE_TRACE_POINTS
+#include <trace/events/lock.h>
+
#ifndef CONFIG_PREEMPT_RT
#include "mutex.h"

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