On Wed, Sep 27, 2023 at 03:14:10PM -0400, Martin K. Petersen wrote: > > Hi Bart! > > > Zoned UFS vendors need the data temperature information. Hence this > > patch series that restores write hint information in F2FS and in the > > block layer. The SCSI disk (sd) driver is modified such that it passes > > write hint information to SCSI devices via the GROUP NUMBER field. > > I don't have any particular problems with your implementation, although > I'm still trying to wrap my head around how to make this coexist with my > I/O hinting series. But I guess there's probably not going to be a big > overlap between devices that support both features. Hello Bart, Martin, I don't know which user facing API Martin's I/O hinting series is intending to use. However, while discussing this series at ALPSS, we did ask ourselves why this series is not reusing the already existing block layer API for providing I/O hints: https://github.com/torvalds/linux/blob/v6.6-rc4/include/uapi/linux/ioprio.h#L83-L103 We can have 1023 possible I/O hints, and so far we are only using 7, which means that there are 1016 possible hints left. This also enables you to define more than the 4 previous temperature hints (extreme, long, medium, short), if so desired. There is also support in fio for these I/O hints: https://github.com/axboe/fio/blob/master/HOWTO.rst?plain=1#L2294-L2302 When this new I/O hint API has added, there was no other I/O hint API in the kernel (since the old fcntl() F_GET_FILE_RW_HINT / F_SET_FILE_RW_HINT API had already been removed when this new API was added). So there should probably be a good argument why we would want to introduce yet another API for providing I/O hints, instead of extending the I/O hint API that we already have in the kernel right now. (Especially since it seems fairly easy to modify your patches to reuse the existing API.) Kind regards, Niklas
