> -----Original Message----- > From: Javier González <javier@xxxxxxxxxxx> > Sent: Tuesday, 15 March 2022 14.26 > To: Matias Bjørling <Matias.Bjorling@xxxxxxx> > Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>; Christoph > Hellwig <hch@xxxxxx>; Luis Chamberlain <mcgrof@xxxxxxxxxx>; Keith Busch > <kbusch@xxxxxxxxxx>; Pankaj Raghav <p.raghav@xxxxxxxxxxx>; Adam > Manzanares <a.manzanares@xxxxxxxxxxx>; jiangbo.365@xxxxxxxxxxxxx; > kanchan Joshi <joshi.k@xxxxxxxxxxx>; Jens Axboe <axboe@xxxxxxxxx>; Sagi > Grimberg <sagi@xxxxxxxxxxx>; Pankaj Raghav <pankydev8@xxxxxxxxx>; > Kanchan Joshi <joshiiitr@xxxxxxxxx>; linux-block@xxxxxxxxxxxxxxx; linux- > nvme@xxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH 0/6] power_of_2 emulation support for NVMe ZNS devices > > On 15.03.2022 13:14, Matias Bjørling wrote: > >> > > >> >All that said - if there are people willing to do the work and it > >> >doesn't have a > >> negative impact on performance, code quality, maintenance complexity, > etc. > >> then there isn't anything saying support can't be added - but it does > >> seem like it’s a lot of work, for little overall benefits to applications and the > host users. > >> > >> Exactly. > >> > >> Patches in the block layer are trivial. This is running in production > >> loads without issues. I have tried to highlight the benefits in > >> previous benefits and I believe you understand them. > >> > >> Support for ZoneFS seems easy too. We have an early POC for btrfs and > >> it seems it can be done. We sign up for these 2. > >> > >> As for F2FS and dm-zoned, I do not think these are targets at the > >> moment. If this is the path we follow, these will bail out at mkfs time. > >> > >> If we can agree on the above, I believe we can start with the code > >> that enables the existing customers and build support for butrfs and > >> ZoneFS in the next few months. > >> > >> What do you think? > > > >I would suggest to do it in a single shot, i.e., a single patchset, which enables > all the internal users in the kernel (including f2fs and others). That way end- > users do not have to worry about the difference of PO2/NPO2 zones and it'll > help reduce the burden on long-term maintenance. > > Thanks for the suggestion Matias. Happy to see that you are open to support > this. I understand why a patchseries fixing all is attracgive, but we do not see a > usage for ZNS in F2FS, as it is a mobile file-system. As other interfaces arrive, > this work will become natural. We've seen uptake on ZNS on f2fs, so I would argue that its important to have support in as well. > > ZoneFS and butrfs are good targets for ZNS and these we can do. I would still do > the work in phases to make sure we have enough early feedback from the > community. Sure, continuous review is good. But not having support for all the kernel users creates fragmentation. Doing a full switch is greatly preferred, as it avoids this fragmentation, but will also lower the overall maintenance burden, which also was raised as a concern.
