Merge pull request #1424 from selvintxavier/db_moderation

bnxt_re/lib: Reduce the Doorbells during SRQ and CQ handling

providers/bnxt_re/main.h

@@ -105,6 +105,8 @@ struct bnxt_re_cq {
  uint32_t mem_handle;
  void *toggle_map;
  uint32_t toggle_size;
+ bool deffered_db_sup;
+ uint32_t hw_cqes;
 };
 
 struct bnxt_re_push_buffer {

providers/bnxt_re/verbs.c

@@ -319,6 +319,12 @@ struct ibv_cq *bnxt_re_create_cq(struct ibv_context *ibvctx, int ncqe,
  if (!cq)
  return NULL;
 
+ /* Enable deferred DB mode for CQ if the CQ is small */
+ if (ncqe * 2 < dev->max_cq_depth) {
+ cq->deffered_db_sup = true;
+ ncqe = 2 * ncqe;
+ }
+
  cq->cqq.depth = bnxt_re_init_depth(ncqe + 1, cntx->comp_mask);
  if (cq->cqq.depth > dev->max_cq_depth + 1)
  cq->cqq.depth = dev->max_cq_depth + 1;
@@ -398,6 +404,16 @@ int bnxt_re_resize_cq(struct ibv_cq *ibvcq, int ncqe)
  if (ncqe > dev->max_cq_depth)
  return -EINVAL;
 
+ /* Check if we can be in defered DB mode with the
+ * newer size of CQE.
+ */
+ if (2 * ncqe > dev->max_cq_depth) {
+ cq->deffered_db_sup = false;
+ } else {
+ ncqe = 2 * ncqe;
+ cq->deffered_db_sup = true;
+ }
+
  pthread_spin_lock(&cq->cqq.qlock);
  cq->resize_cqq.depth = bnxt_re_init_depth(ncqe + 1, cntx->comp_mask);
  if (cq->resize_cqq.depth > dev->max_cq_depth + 1)
@@ -754,6 +770,21 @@ static uint8_t bnxt_re_poll_term_cqe(struct bnxt_re_qp *qp, int *cnt)
  return 0;
 }
 
+static inline void bnxt_re_check_and_ring_cq_db(struct bnxt_re_cq *cq,
+ int *hw_polled)
+{
+ /* Ring doorbell only if the CQ is at
+ * least half when deferred db mode is active
+ */
+ if (cq->deffered_db_sup) {
+ if (cq->hw_cqes < cq->cqq.depth / 2)
+ return;
+ *hw_polled = 0;
+ cq->hw_cqes = 0;
+ }
+ bnxt_re_ring_cq_db(cq);
+}
+
 static int bnxt_re_poll_one(struct bnxt_re_cq *cq, int nwc, struct ibv_wc *wc,
  uint32_t *resize)
 {
@@ -819,6 +850,7 @@ static int bnxt_re_poll_one(struct bnxt_re_cq *cq, int nwc, struct ibv_wc *wc,
  goto skipp_real;
 
  hw_polled++;
+ cq->hw_cqes++;
  if (qp_handle) {
  *qp_handle = 0x0ULL; /* mark cqe as read */
  qp_handle = NULL;
@@ -832,10 +864,13 @@ static int bnxt_re_poll_one(struct bnxt_re_cq *cq, int nwc, struct ibv_wc *wc,
  nwc--;
  wc++;
  }
+ /* Extra check required to avoid CQ full */
+ if (cq->deffered_db_sup)
+ bnxt_re_check_and_ring_cq_db(cq, &hw_polled);
  }
 
  if (likely(hw_polled))
- bnxt_re_ring_cq_db(cq);
+ bnxt_re_check_and_ring_cq_db(cq, &hw_polled);
 
  return dqed;
 }
@@ -2152,12 +2187,12 @@ int bnxt_re_query_srq(struct ibv_srq *ibvsrq, struct ibv_srq_attr *attr)
  return ibv_cmd_query_srq(ibvsrq, attr, &cmd, sizeof(cmd));
 }
 
-static int bnxt_re_build_srqe(struct bnxt_re_srq *srq,
- struct ibv_recv_wr *wr, void *srqe)
+static void bnxt_re_build_srqe(struct bnxt_re_srq *srq,
+  struct ibv_recv_wr *wr, void *srqe)
 {
  struct bnxt_re_brqe *hdr = srqe;
- struct bnxt_re_sge *sge;
  struct bnxt_re_wrid *wrid;
+ struct bnxt_re_sge *sge;
  int wqe_sz, len, next;
  uint32_t hdrval = 0;
  int indx;
@@ -2184,17 +2219,16 @@ static int bnxt_re_build_srqe(struct bnxt_re_srq *srq,
  wrid->wrid = wr->wr_id;
  wrid->bytes = len; /* N.A. for RQE */
  wrid->sig = 0; /* N.A. for RQE */
-
- return len;
 }
 
 int bnxt_re_post_srq_recv(struct ibv_srq *ibvsrq, struct ibv_recv_wr *wr,
  struct ibv_recv_wr **bad)
 {
  struct bnxt_re_srq *srq = to_bnxt_re_srq(ibvsrq);
  struct bnxt_re_queue *rq = srq->srqq;
+ int count = 0, rc = 0;
+ bool ring_db = false;
  void *srqe;
- int ret, count = 0;
 
  pthread_spin_lock(&rq->qlock);
  count = rq->tail > rq->head ? rq->tail - rq->head :
@@ -2203,32 +2237,32 @@ int bnxt_re_post_srq_recv(struct ibv_srq *ibvsrq, struct ibv_recv_wr *wr,
  if (srq->start_idx == srq->last_idx ||
  wr->num_sge > srq->cap.max_sge) {
  *bad = wr;
- pthread_spin_unlock(&rq->qlock);
- return ENOMEM;
+ rc = ENOMEM;
+ goto exit;
  }
 
  srqe = (void *) (rq->va + (rq->tail * rq->stride));
  memset(srqe, 0, bnxt_re_get_srqe_sz());
- ret = bnxt_re_build_srqe(srq, wr, srqe);
- if (ret < 0) {
- pthread_spin_unlock(&rq->qlock);
- *bad = wr;
- return ENOMEM;
- }
+ bnxt_re_build_srqe(srq, wr, srqe);
 
  srq->start_idx = srq->srwrid[srq->start_idx].next_idx;
  bnxt_re_incr_tail(rq, 1);
+ ring_db = true;
  wr = wr->next;
- bnxt_re_ring_srq_db(srq);
  count++;
  if (srq->arm_req == true && count > srq->cap.srq_limit) {
  srq->arm_req = false;
+ ring_db = false;
+ bnxt_re_ring_srq_db(srq);
  bnxt_re_ring_srq_arm(srq);
  }
  }
+exit:
+ if (ring_db)
+ bnxt_re_ring_srq_db(srq);
  pthread_spin_unlock(&rq->qlock);
 
- return 0;
+ return rc;
 }
 
 struct ibv_ah *bnxt_re_create_ah(struct ibv_pd *ibvpd, struct ibv_ah_attr *attr)