+/*
+ * Update dispatch busy with EWMA:

Please expand the EWMA acronym.

+static void blk_mq_update_hctx_busy(struct blk_mq_hw_ctx *hctx, bool busy)
+{
+	const unsigned weight = 8;
+	unsigned int ewma;
+
+	if (hctx->queue->elevator)
+		return;
+
+	ewma = READ_ONCE(hctx->dispatch_busy);
+
+	ewma *= weight - 1;
+	if (busy)
+		ewma += 16;

plese use descriptive all upper case #defines for the WEIGHT and FACTOR
so that they stick out.