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

diff --git a/include/trace/events/lock.h b/include/trace/events/lock.h
index d7512129a324e5de49e1cafb8a7856a63324c989..b9b6e3edd518390e74c66ce355b729e3d4abf096 100644 (file)
--- 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 3cbd49216174d34eaf9b889aeae60b244b9b1268..a6e671b8608dbd12acd1c82a5faca189b3771113 100644 (file)
--- 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 5e3585950ec8f7d353c7e8ff9b91d21464ee0b75..ee2fd7614a9352797aa87f93d939e9e2ad89b80e 100644 (file)
--- 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"