ring-buffer: Incorporate absolute timestamp into add_timestamp logic (7c4b4a51) · Commits · 戴 / test

kernel/trace/ring_buffer.c

+22 −18

Original line number	Diff line number	Diff line
		@@ -422,13 +422,15 @@ struct rb_event_info {
		/*
		* Used for the add_timestamp
		* NONE
		* NORMAL - may be for either time extend or absolute
		* EXTEND - wants a time extend
		* ABSOLUTE - the buffer requests all events to have absolute time stamps
		* FORCE - force a full time stamp.
		*/
		enum {
		RB_ADD_STAMP_NONE,
		RB_ADD_STAMP_NORMAL,
		RB_ADD_STAMP_FORCE
		RB_ADD_STAMP_NONE = 0,
		RB_ADD_STAMP_EXTEND = BIT(1),
		RB_ADD_STAMP_ABSOLUTE = BIT(2),
		RB_ADD_STAMP_FORCE = BIT(3)
		};
		/*
		* Used for which event context the event is in.
		@@ -2434,8 +2436,8 @@ rb_update_event(struct ring_buffer_per_cpu *cpu_buffer,
		* add it to the start of the reserved space.
		*/
		if (unlikely(info->add_timestamp)) {
		bool abs = info->add_timestamp == RB_ADD_STAMP_FORCE \|\|
		ring_buffer_time_stamp_abs(cpu_buffer->buffer);
		bool abs = info->add_timestamp &
		(RB_ADD_STAMP_FORCE \| RB_ADD_STAMP_ABSOLUTE);

		event = rb_add_time_stamp(event, abs ? info->delta : delta, abs);
		length -= RB_LEN_TIME_EXTEND;
		@@ -2884,7 +2886,7 @@ int ring_buffer_unlock_commit(struct trace_buffer *buffer,
		EXPORT_SYMBOL_GPL(ring_buffer_unlock_commit);

		static noinline void
		rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
		rb_check_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
		struct rb_event_info *info)
		{
		WARN_ONCE(info->delta > (1ULL << 59),
		@@ -2897,7 +2899,6 @@ rb_handle_timestamp(struct ring_buffer_per_cpu *cpu_buffer,
		"please switch to the trace global clock:\n"
		" echo global > /sys/kernel/debug/tracing/trace_clock\n"
		"or add trace_clock=global to the kernel command line\n");
		info->add_timestamp = RB_ADD_STAMP_NORMAL;
		}

		static struct ring_buffer_event *
		@@ -2908,7 +2909,6 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
		struct buffer_page *tail_page;
		unsigned long tail, write, w;
		u64 before, after;
		bool abs = false;

		/* Don't let the compiler play games with cpu_buffer->tail_page */
		tail_page = info->tail_page = READ_ONCE(cpu_buffer->tail_page);
		@@ -2922,20 +2922,23 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,

		if (ring_buffer_time_stamp_abs(cpu_buffer->buffer)) {
		info->delta = info->ts;
		abs = true;
		info->add_timestamp = RB_ADD_STAMP_ABSOLUTE;
		} else {
		info->delta = info->ts - after;
		}

		if (unlikely(test_time_stamp(info->delta)))
		rb_handle_timestamp(cpu_buffer, info);
		if (unlikely(test_time_stamp(info->delta))) {
		rb_check_timestamp(cpu_buffer, info);
		info->add_timestamp \|= RB_ADD_STAMP_EXTEND;
		}

		/*
		* If interrupting an event time update, we may need an absolute timestamp.
		* Don't bother if this is the start of a new page (w == 0).
		*/
		if (unlikely(before != after && w))
		info->add_timestamp = RB_ADD_STAMP_FORCE;
		info->add_timestamp \|= RB_ADD_STAMP_FORCE \| RB_ADD_STAMP_EXTEND;

		/*
		* If the time delta since the last event is too big to
		* hold in the time field of the event, then we append a
		@@ -2972,7 +2975,8 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
		/D/ local64_set(&cpu_buffer->write_stamp, info->ts);
		barrier();
		/E/ save_before = local64_read(&cpu_buffer->before_stamp);
		if (likely(info->add_timestamp != RB_ADD_STAMP_FORCE))
		if (likely(!(info->add_timestamp &
		(RB_ADD_STAMP_FORCE \| RB_ADD_STAMP_ABSOLUTE))))
		/* This did not interrupt any time update */
		info->delta = info->ts - after;
		else
		@@ -3015,15 +3019,15 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
		*/
		info->delta = 0;
		}
		if (info->add_timestamp == RB_ADD_STAMP_FORCE)
		info->add_timestamp = RB_ADD_STAMP_NORMAL;
		info->add_timestamp &= ~RB_ADD_STAMP_FORCE;
		}

		/*
		* If this is the first commit on the page, then it has the same
		* timestamp as the page itself.
		*/
		if (unlikely(!tail && info->add_timestamp != RB_ADD_STAMP_FORCE && !abs))
		if (unlikely(!tail && !(info->add_timestamp &
		(RB_ADD_STAMP_FORCE \| RB_ADD_STAMP_ABSOLUTE))))
		info->delta = 0;

		/* We reserved something on the buffer */

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