tree 83f100a6bb0ee810859baf32ec1850c1a588edfd
parent 4366b19ca5eb15e63d6640565ade135cf06be91a
author Jenny Derzhavetz <jennyf@mellanox.com> 1441540346 +0300
committer Nicholas Bellinger <nab@linux-iscsi.org> 1442357251 -0700

iser-target: Skip data copy if all the command data comes as immediate

Given that supporting zcopy immediate data for all IOs requires
iser driver to use its own buffer allocations, we settle with
avoiding data copy for IOs with data length of up to 8K (which
is more latency sensitive anyway).

This trims IO write latency by up to 3us and increase IOPs
by up to 40% by saving CPU time doing sg_copy_from_buffer
(8K IO size is the obvious winner here).

Signed-off-by: Jenny Derzhavetz <jennyf@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>