On Wed, 16 Mar 2022 15:45:47 -0700
Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
> 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@xxxxxxxxxx>
> ---
> include/trace/events/lock.h | 54 ++++++++++++++++++++++++++++++++++---
> kernel/locking/lockdep.c | 1 -
> kernel/locking/mutex.c | 3 +++
> 3 files changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/include/trace/events/lock.h b/include/trace/events/lock.h
> index d7512129a324..2a3df36d4fdb 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 +88,46 @@ 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=%x)", __entry->lock_addr, __entry->flags)
Perhaps make this into:
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" }
))
That way, the use doesn't need to figure out what the numbers mean.
-- Steve
> +);
> +
> +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 50036c10b518..08f8fb6a2d1e 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 5e3585950ec8..ee2fd7614a93 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"
>
