Total flight time is Chocks to chocks, IMC time is logged as Instument flying, deck time is part of the total time.
5 minute taxi either end, 10 minute deck time, 1 hour Instrument, 2 hour flight time. Log book entry would be total time 2 hours 20 minutes with 1 hour instrument. P1 or P2 as required.
Many years ago the then Chief Pilot of BIH tried to have the ground time/taxi time deducted from log book hours. It took a letter from the CAA to point out that this was not correct.