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IB/ehca: Replace modulus operations in flush error completion path

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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 <stefan.roscher@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Stefan Roscher 2008-12-05 11:25:38 -08:00 committed by Roland Dreier
parent 75c21ae9aa
commit 1c721940dd
3 changed files with 19 additions and 13 deletions
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7
drivers/infiniband/hw/ehca/ehca_classes.h
View file

@ -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;

12
drivers/infiniband/hw/ehca/ehca_qp.c
View file

@ -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);
}

13
drivers/infiniband/hw/ehca/ehca_reqs.c
View file

@ -726,13 +726,13 @@ static inline int ehca_poll_cq_one(struct ib_cq *cq, struct ib_wc *wc)
* 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++;