> Since there is a desire to remove the write hint information from struct bio, is > there any other information the "system data characteristics" information > can be derived from? > How about e.g. deriving that information from request flags like REQ_SYNC, > REQ_META and/or REQ_IDLE? Bart, I agree with all your analysis. The point is these flags (Sync, Meta and Idle) are really meant for latency management whereas here the problem is hot/cold separation. At this moment I am not aware of any methodology we can use to map S/M/Idle flags Into hot/cold meaning but I am open to talk and discuss :-) > > Thanks, > > Bart. Cheers, Luca