sorry for not being clear again. by saying this number does not represent full fsync operation, I meant it doesn't include the SSD write time. this is the time to update KVs internal memory structure + adding to write buffers.

this is fair because we provide transactional guarantee and immediate consistency, regardless of the state of the append-only write buffer entry. during that speed, for a given key, the value might change and a new write buffer entry might be added for the said key before the write buffer had the chance to complete (as you mentioned the actual write on disk is slower) but the conflict resolution still ensures the write of the last valid entry and skips the rest. before this operation HPKV is acting like an in-memory KV store.