Having used this flight a few times I really see no reason at all to attempt eating on the plane. Ex-HKG the Pier F offers excellent dining. Ex-HEL you can either have a nice meal in town or at home, or some pretty nice tasting nibbles in the premium lounge.
I try to go to sleep ASAP on these flights, but yes last time ex-HEL I noticed it took well over 2hrs until dinner service was ended (I had finished my 2hr film anyway!).