Re: [PATCHv10 0/9] write hints with nvme fdp, scsi streams

[Javier Gonzalez <javier.gonz@samsung.com>]

On 11.11.2024 09:43, Johannes Thumshirn wrote:
>On 11.11.24 10:41, Javier Gonzalez wrote:
>> On 11.11.2024 09:37, Johannes Thumshirn wrote:
>>> On 11.11.24 10:31, Javier Gonzalez wrote:
>>>> On 11.11.2024 07:51, Christoph Hellwig wrote:
>>>>> On Fri, Nov 08, 2024 at 05:43:44PM +0000, Javier Gonzalez wrote:
>>>>>> We have been iterating in the patches for years, but it is unfortunately
>>>>>> one of these series that go in circles forever. I don't think it is due
>>>>>> to any specific problem, but mostly due to unaligned requests form
>>>>>> different folks reviewing. Last time I talked to Damien he asked me to
>>>>>> send the patches again; we have not followed through due to bandwidth.
>>>>>
>>>>> A big problem is that it actually lacks a killer use case.  If you'd
>>>>> actually manage to plug it into an in-kernel user and show a real
>>>>> speedup people might actually be interested in it and help optimizing
>>>>> for it.
>>>>>
>>>>
>>>> Agree. Initially it was all about ZNS. Seems ZUFS can use it.
>>>>
>>>> Then we saw good results in offload to target on NVMe-OF, similar to
>>>> copy_file_range, but that does not seem to be enough. You seem to
>>>> indicacte too that XFS can use it for GC.
>>>>
>>>> We can try putting a new series out to see where we are...
>>>
>>> I don't want to sound like a broken record, but I've said more than
>>> once, that btrfs (regardless of zoned or non-zoned) would be very
>>> interested in that as well and I'd be willing to help with the code or
>>> even do it myself once the block bits are in.
>>>
>>> But apparently my voice doesn't count here
>>
>> You are right. Sorry I forgot.
>>
>> Would this be through copy_file_range or something different?
>>
>
>Unfortunately not, brtfs' reclaim/balance path is a wrapper on top of
>buffered read and write (plus some extra things). _BUT_ this makes it
>possible to switch the read/write part and do copy offload (where possible).

On 11.11.2024 10:42, hch wrote:
>On Mon, Nov 11, 2024 at 10:41:33AM +0100, Javier Gonzalez wrote:
>> You are right. Sorry I forgot.
>>
>> Would this be through copy_file_range or something different?
>
>Just like for f2fs, nilfs2, or the upcoming zoned xfs the prime user
>would be the file system GC code.

Replying to both.

Thanks. Makes sense. Now that we can talke a look at your branch, we can
think how this would look like.