As proposed by the SRP (draft) standard, ib_srp reserves one ring element for SRP_TSK_MGMT requests. This patch makes sure that the SCSI mid-layer never tries to queue more than (SRP request limit) - 1 SCSI commands to ib_srp. This improves performance for targets whose request limit is less than or equal to SRP_SQ_REQ_SIZE - SRP_TSK_MGMT_RSV (62) by reducing the number of BUSY responses reported by ib_srp to the SCSI mid-layer.
Signed-off-by: Bart Van Assche <[email protected]> Cc: Roland Dreier <[email protected]> Cc: David Dillow <[email protected]> --- drivers/infiniband/ulp/srp/ib_srp.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index cc6a713..93d6d0f 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -1354,8 +1354,13 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event) target->max_ti_iu_len = be32_to_cpu(rsp->max_ti_iu_len); target->req_lim = be32_to_cpu(rsp->req_lim_delta); - target->scsi_host->can_queue = min(target->req_lim, - target->scsi_host->can_queue); + /* + * Set can_queue such that the SCSI mid-layer + * never causes __srp_get_tx_iu() to fail. + */ + target->scsi_host->can_queue + = min(target->req_lim - SRP_TSK_MGMT_RSV, + target->scsi_host->can_queue); } else { shost_printk(KERN_WARNING, target->scsi_host, PFX "Unhandled RSP opcode %#x\n", opcode); -- 1.6.4.2 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
