From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx> Hi folks, This series addresses a v3.12 starvation regression in iscsi-target after the conversion to use percpu_ida tag preallocation for all iscsi_cmd descriptors. The first patch addresses an unnecessary overhead during iscsi_cmd acknowledgement -> release, that could end up causing an extra context switch to occur for WRITEs. With the advent of proper se_cmd->cmd_kref handling in v3.10, this is no longer required in the acknowledgement fast path. The second patch converts iscsit_ack_from_expstatsn() to populate a local list of acknowledged iscsi_cmd descriptors, and releases them as quickly as possible (and the associated percpu_ida tags) directly from RX thread context. The third patch adds another (tag_num / 2) extra pre-allocated tags, in order to prevent percpu_ida_alloc() from needing to steal tags when the number of acknowledged tags in use is large, seperate from the tags for the CmdSN window depth. I'll be including into target-pending/master shortly, and sending off a PULL request to include for v3.12-rc4 over the next days. Thanks, --nab Nicholas Bellinger (3): iscsi-target: Only perform wait_for_tasks when performing shutdown iscsi-target: Perform release of acknowledged tags from RX context iscsi-target; Allow an extra tag_num / 2 number of percpu_ida tags drivers/target/iscsi/iscsi_target.c | 13 +++++++++---- drivers/target/iscsi/iscsi_target_nego.c | 2 +- drivers/target/iscsi/iscsi_target_util.c | 4 ++-- 3 files changed, 12 insertions(+), 7 deletions(-) -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
