On 2020/06/16 22:32, Judy Brock wrote: > Ok last comment. I should have read Damien's explanation more carefully. I'm > backing off... I see it's having to do with needing to preserve write order/ > zone write locking - a lot of knowledge I don't have about the Linux storage > stack (but I see that is the performance penalty he's referring to now which > makes sense if one really did have to lose the overlapped write capability > with non-Append-capable ZNS drives). Yes, that is what I meant. Regular writes need special treatment to preserve ordering and that has potentially performance implications. > > "To allow other ZNS drives, an emulation similar to SCSI can be implemented, > with that emulation ideally combined to work for both types of drives if > possible. And note that this emulation would require the drive to be operated > with mq-deadline to enable zone write locking for preserving write command > order" > > But of course that is not what we want to do with ZRWA-capable ZNS drives. This is an on-going NVMe technical proposal under NDA, so I will refrain from any comment about this on this public mailing list. -- Damien Le Moal Western Digital Research
