Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753384AbYLBPen (ORCPT ); Tue, 2 Dec 2008 10:34:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750956AbYLBPee (ORCPT ); Tue, 2 Dec 2008 10:34:34 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:41579 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750763AbYLBPed (ORCPT ); Tue, 2 Dec 2008 10:34:33 -0500 From: Stefan Roscher To: "LinuxPPC-Dev" , "OF-EWG" , LKML , Roland Dreier Subject: [PATCH] IB/ehca: replace modulus operations in flush error completion path Date: Tue, 2 Dec 2008 16:31:56 +0100 User-Agent: KMail/1.9.9 Cc: raisch@de.ibm.com, hnguyen@de.ibm.com, fenkes@de.ibm.com, alexschm@de.ibm.com, stefan.roscher@de.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200812021631.58810.ossrosch@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4376 Lines: 112 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 in error path. Signed-off-by: Stefan Roscher --- 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 7fc35cf..c825142 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 cadbf0c..f161cf1 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 00a648f..c711268 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++; -- 1.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/