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
"Need" in what sense? Can you quantify what improvements we might
see from this patchset?
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."
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.