Bring 6 cups broth, barley, and mushrooms to boil in large saucepan. Cover; cook over medium-low heat until barley is just tender, stirring occasionally and adding more broth by 1/4 cupfuls if barley becomes dry, about 35 minutes.
Meanwhile, melt butter in large skillet over medium-high heat. Add onion; sprinkle lightly with salt and pepper. sauté until golden brown, about 10 minutes. Add pear and sauté until just tender, about 5 minutes. Add turkey.
Add barley mixture and Marsala to turkey mixture. Simmer until creamy, adding more broth if dry. Mix in most of parsley. Season with pepper. Mound in bowl. Sprinkle with remaining parsley.