IB/iser: Use IB_WR_REG_MR_INTEGRITY for PI handover
Using this new API reduces iSER code complexity.
It also reduces the maximum number of work requests per task and the need
of dealing with multiple MRs (and their registrations and invalidations)
per task. It is done by using a single WR and a special MR type
(IB_MR_TYPE_INTEGRITY) for PI operation.
The setup of the tested benchmark:
- 2 servers with 24 cores (1 initiator and 1 target)
- 24 target sessions with 1 LUN each
- ramdisk backstore
- PI active
Performance results running fio (24 jobs, 128 iodepth) using
write_generate=0 and read_verify=0 (w/w.o patch):
We get performance improvement at all block sizes.
The most significant improvement is when writing 4k bs (almost 30% more
iops).
Signed-off-by: Israel Rukshin <israelr@mellanox.com> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>