From 1c721940ddd6496508f1f2fde5167b1c898b419b Mon Sep 17 00:00:00 2001 From: Stefan Roscher Date: Fri, 5 Dec 2008 11:25:38 -0800 Subject: [PATCH] IB/ehca: Replace modulus operations in flush error completion path With the latest flush error completion patch we introduced modulus operation to calculate the next index within a qmap. Based on comments from other mailing lists we decided to optimize this operation by using an addition and an if-statement instead of modulus, even though this is on the error path. Signed-off-by: Stefan Roscher Signed-off-by: Roland Dreier --- drivers/infiniband/hw/ehca/ehca_classes.h | 7 +++++++ drivers/infiniband/hw/ehca/ehca_qp.c | 12 ++++++------ drivers/infiniband/hw/ehca/ehca_reqs.c | 13 ++++++------- 3 files changed, 19 insertions(+), 13 deletions(-) diff --git a/drivers/infiniband/hw/ehca/ehca_classes.h b/drivers/infiniband/hw/ehca/ehca_classes.h index 7fc35cf0cdd..c825142a2fb 100644 --- a/drivers/infiniband/hw/ehca/ehca_classes.h +++ b/drivers/infiniband/hw/ehca/ehca_classes.h @@ -175,6 +175,13 @@ struct ehca_queue_map { unsigned int next_wqe_idx; /* Idx to first wqe to be flushed */ }; +/* function to calculate the next index for the qmap */ +static inline unsigned int next_index(unsigned int cur_index, unsigned int limit) +{ + unsigned int temp = cur_index + 1; + return (temp == limit) ? 0 : temp; +} + struct ehca_qp { union { struct ib_qp ib_qp; diff --git a/drivers/infiniband/hw/ehca/ehca_qp.c b/drivers/infiniband/hw/ehca/ehca_qp.c index cadbf0cdd91..f161cf173db 100644 --- a/drivers/infiniband/hw/ehca/ehca_qp.c +++ b/drivers/infiniband/hw/ehca/ehca_qp.c @@ -1138,14 +1138,14 @@ static int calc_left_cqes(u64 wqe_p, struct ipz_queue *ipz_queue, return -EFAULT; } - tail_idx = (qmap->tail + 1) % qmap->entries; + tail_idx = next_index(qmap->tail, qmap->entries); wqe_idx = q_ofs / ipz_queue->qe_size; /* check all processed wqes, whether a cqe is requested or not */ while (tail_idx != wqe_idx) { if (qmap->map[tail_idx].cqe_req) qmap->left_to_poll++; - tail_idx = (tail_idx + 1) % qmap->entries; + tail_idx = next_index(tail_idx, qmap->entries); } /* save index in queue, where we have to start flushing */ qmap->next_wqe_idx = wqe_idx; @@ -1195,14 +1195,14 @@ static int check_for_left_cqes(struct ehca_qp *my_qp, struct ehca_shca *shca) } else { spin_lock_irqsave(&my_qp->send_cq->spinlock, flags); my_qp->sq_map.left_to_poll = 0; - my_qp->sq_map.next_wqe_idx = (my_qp->sq_map.tail + 1) % - my_qp->sq_map.entries; + my_qp->sq_map.next_wqe_idx = next_index(my_qp->sq_map.tail, + my_qp->sq_map.entries); spin_unlock_irqrestore(&my_qp->send_cq->spinlock, flags); spin_lock_irqsave(&my_qp->recv_cq->spinlock, flags); my_qp->rq_map.left_to_poll = 0; - my_qp->rq_map.next_wqe_idx = (my_qp->rq_map.tail + 1) % - my_qp->rq_map.entries; + my_qp->rq_map.next_wqe_idx = next_index(my_qp->rq_map.tail, + my_qp->rq_map.entries); spin_unlock_irqrestore(&my_qp->recv_cq->spinlock, flags); } diff --git a/drivers/infiniband/hw/ehca/ehca_reqs.c b/drivers/infiniband/hw/ehca/ehca_reqs.c index 00a648f4316..c7112686782 100644 --- a/drivers/infiniband/hw/ehca/ehca_reqs.c +++ b/drivers/infiniband/hw/ehca/ehca_reqs.c @@ -726,13 +726,13 @@ repoll: * set left_to_poll to 0 because in error state, we will not * get any additional CQEs */ - my_qp->sq_map.next_wqe_idx = (my_qp->sq_map.tail + 1) % - my_qp->sq_map.entries; + my_qp->sq_map.next_wqe_idx = next_index(my_qp->sq_map.tail, + my_qp->sq_map.entries); my_qp->sq_map.left_to_poll = 0; ehca_add_to_err_list(my_qp, 1); - my_qp->rq_map.next_wqe_idx = (my_qp->rq_map.tail + 1) % - my_qp->rq_map.entries; + my_qp->rq_map.next_wqe_idx = next_index(my_qp->rq_map.tail, + my_qp->rq_map.entries); my_qp->rq_map.left_to_poll = 0; if (HAS_RQ(my_qp)) ehca_add_to_err_list(my_qp, 0); @@ -860,9 +860,8 @@ static int generate_flush_cqes(struct ehca_qp *my_qp, struct ib_cq *cq, /* mark as reported and advance next_wqe pointer */ qmap_entry->reported = 1; - qmap->next_wqe_idx++; - if (qmap->next_wqe_idx == qmap->entries) - qmap->next_wqe_idx = 0; + qmap->next_wqe_idx = next_index(qmap->next_wqe_idx, + qmap->entries); qmap_entry = &qmap->map[qmap->next_wqe_idx]; wc++; nr++; -- 2.41.1