On Wed, Sep 20, 2023 at 01:46:41PM -0700, Bart Van Assche wrote: > On 9/20/23 12:28, Matthew Wilcox wrote: > > On Wed, Sep 20, 2023 at 12:14:25PM -0700, Bart Van Assche wrote: > > > 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. > > > > "Need" in what sense? Can you quantify what improvements we might see > > from this patchset? > > Hi Matthew, > > This is what Jens wrote about 1.5 years ago in reply to complaints about > the removal of write hint support making it impossible to pass write hint > information to SSD devices: "If at some point there's a > desire to actually try and upstream this support, then we'll be happy to > review that patchset." > (https://lore.kernel.org/linux-block/ef77ef36-df95-8658-ff54-7d8046f5d0e7@xxxxxxxxx/). > Hence this patch series. > > Recently T10 standardized how data temperature information should be passed > to SCSI devices. One of the patches in this series translates write hint > information into a data temperature for SCSI devices. This can be used by > SCSI SSD devices (including UFS devices) to reduce write amplification > inside the device because host software should assign the same data > temperature to all data that will be garbage collected at once. Hello Bart, Considering that this API (F_GET_FILE_RW_HINT / F_SET_FILE_RW_HINT) was previously only used by NVMe (NVMe streams). Yet, this API and the support in NVMe (NVMe streams) was removed. Now you want to re-add the same API, but this time, it will only be used by SCSI. Since you basically revert (some of) the patches, I would have expected the cover letter to at least mention NVMe somewhere. Should NVMe streams be brought back? Yes? No? While I have a strong guess of what the NVMe maintainers will say, I think that your cover letter should mention "why"/"why not" the NVMe support "is"/"is not" reverted. Kind regards, Niklas
