Re: [PATCH v2 0/5] tracepoints: Add warnings for unused tracepoints and trace events

Steven Rostedt Fri, 13 Jun 2025 07:43:29 -0700

On Fri, 13 Jun 2025 10:28:34 -0400
Steven Rostedt <rost...@goodmis.org> wrote:


> And each DEFINE_EVENT() is approximately 1296 bytes.
>   ((19559 - 2069) - 5819) / 9

Interesting enough, just raw tracepoints are not much better. I updated
the header file (attached) to have 10 of these, and compiled that.

DECLARE_TRACE(size_event_1,
        TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
        TP_ARGS(A, B));

The result is:

   text    data     bss     dec     hex filename
    629    1440       0    2069     815 no-events.ko
  44837   15424       0   60261    eb65 trace-events.ko
  11495    8064       0   19559    4c67 define-events.ko
  10865    4408       0   15273    3ba9 declare-trace.ko

Where each DECLARE_TRACE() ends up being 1320 bytes.
  (15273 - 2069) / 10

This is slightly bigger than a DEFINE_EVENT(), but that's also because
the DEFINE_EVENT() shares some of the tracepoint creation in the
DECLARE_EVENT_CLASS(), where as that work is done fully in the
DECLARE_TRACE().

-- Steve

/* SPDX-License-Identifier: GPL-2.0 */
#undef TRACE_SYSTEM
#define TRACE_SYSTEM event-sizes 

#undef TRACE_SYSTEM_VAR
#define TRACE_SYSTEM_VAR event_sizes

#if !defined(_SIZE_EVENT_H) || defined(TRACE_HEADER_MULTI_READ)
#define _SIZE_EVENT_H

#include <linux/tracepoint.h>

#ifndef SIZE_EVENT_DEFINED
#define SIZE_EVENT_DEFINED
struct size_event_struct {
	unsigned long a;
	unsigned long b;
};
#endif

#define DEFINE_EVENT_SIZES 0
#define DEFINE_FULL_EVENTS 0
#define DEFINE_JUST_TRACEPOINTS 1

#if DEFINE_EVENT_SIZES

TRACE_EVENT(size_event_1,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);

#if DEFINE_FULL_EVENTS
TRACE_EVENT(size_event_2,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_3,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_4,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_5,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_6,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_7,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_8,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_9,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
TRACE_EVENT(size_event_10,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B),
	TP_STRUCT__entry(
		__field(	unsigned long,	Aa)
		__field(	unsigned long,	Ab)
		__field(	unsigned long,	Ba)
		__field(	unsigned long,	Bb)
	),
	TP_fast_assign(
		__entry->Aa = A->a;
		__entry->Ab = A->b;
		__entry->Ba = B->a;
		__entry->Bb = B->b;
	),
	TP_printk("Aa=%ld Ab=%ld Ba=%ld Bb=%ld",
		__entry->Aa, __entry->Ab, __entry->Ba, __entry->Bb)
);
#else /* !DEFINE_FULL_EVENTS */
DEFINE_EVENT(size_event_1, size_event_2,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_3,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_4,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_5,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_6,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_7,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_8,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_9,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DEFINE_EVENT(size_event_1, size_event_10,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

#endif /* !DEFINE_FULL_EVENTS */

#elif DEFINE_JUST_TRACEPOINTS

DECLARE_TRACE(size_event_1,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_2,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_3,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_4,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_5,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_6,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_7,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_8,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_9,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));

DECLARE_TRACE(size_event_10,
	TP_PROTO(struct size_event_struct *A, struct size_event_struct *B),
	TP_ARGS(A, B));
#endif /* DEFINE_EVENT_SIZES && DEFINE_JUST_TRACEPOINTS */

#endif

/***** NOTICE! The #if protection ends here. *****/


#undef TRACE_INCLUDE_PATH
#undef TRACE_INCLUDE_FILE
#define TRACE_INCLUDE_PATH .
#define TRACE_INCLUDE_FILE size_events 
#include <trace/define_trace.h>

Re: [PATCH v2 0/5] tracepoints: Add warnings for unused tracepoints and trace events

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