Re: [PATCH 0/6] power_of_2 emulation support for NVMe ZNS devices

Javier González
2022-03-15T13:28:12Z

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.

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.

Since this thread has been very active, I will wait some time for
Christoph and others to catch up before we start sending code.