[...]

quoted

+static struct ring_buffer_event *
+simple_rb_reserve_next(struct simple_rb_per_cpu *cpu_buffer, unsigned long length, u64 timestamp)
+{
+	unsigned long ts_ext_size = 0, event_size = rb_event_size(length);
+	struct simple_buffer_page *tail = cpu_buffer->tail_page;
+	struct ring_buffer_event *event;
+	u32 write, prev_write;
+	u64 time_delta;
+
+	time_delta = timestamp - cpu_buffer->write_stamp;

The remote buffers never get preempted do they?

That is, it doesn't need to handle different contexts like the normal
kernel does? (normal, softirq, irq, NMI, etc).

No, luckily, we don't need to support any of that.

-- Steve

quoted

+
+	if (test_time_stamp(time_delta))
+		ts_ext_size = 8;
+
+	prev_write = tail->write;
+	write = prev_write + event_size + ts_ext_size;
+
+	if (unlikely(write > (PAGE_SIZE - BUF_PAGE_HDR_SIZE)))
+		tail = simple_rb_move_tail(cpu_buffer);
+
+	if (!tail->entries) {
+		tail->page->time_stamp = timestamp;
+		time_delta = 0;
+		ts_ext_size = 0;
+		write = event_size;
+		prev_write = 0;
+	}
+
+	tail->write = write;
+	tail->entries++;
+
+	cpu_buffer->write_stamp = timestamp;
+
+	event = (struct ring_buffer_event *)(tail->page->data + prev_write);
+	if (ts_ext_size) {
+		event = rb_event_add_ts_extend(event, time_delta);
+		time_delta = 0;
+	}
+
+	event->type_len = 0;
+	event->time_delta = time_delta;
+	event->array[0] = event_size - RB_EVNT_HDR_SIZE;
+
+	return event;
+}
+