This is also very interesting for storage targets, which face the same
issue. SCST has a mode where it caches some fully constructed SGLs,
which is probably very similar to what NICs want to do.
I think a cached allocator for page sets + the scatterlists that
describe these page sets would not only be useful for SCSI target
implementations but also for the Linux SCSI initiator. Today the scsi-mq
code reserves space in each scsi_cmnd for a scatterlist of
SCSI_MAX_SG_SEGMENTS. If scatterlists would be cached together with page
sets less memory would be needed per scsi_cmnd.
If we go down this road how about also attaching some driver opaques
to the page sets?
I know of some drivers that can make good use of those ;)
