From 6022943eb4cb3cb9e43f27f1faeaba38e162d966 Mon Sep 17 00:00:00 2001 From: Bryan O'Sullivan Date: Thu, 28 Sep 2006 08:59:57 -0700 Subject: IB/ipath: Limit # of packets sent without an ACK received The sender requests an ACK every 1/2 MB to avoid retransmit timeouts that were causing MVAPICH mod_bw to fail after a predictable number of sends. Signed-off-by: Bryan O'Sullivan Signed-off-by: Roland Dreier --- drivers/infiniband/hw/ipath/ipath_rc.c | 47 +++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 18 deletions(-) (limited to 'drivers/infiniband/hw/ipath/ipath_rc.c') diff --git a/drivers/infiniband/hw/ipath/ipath_rc.c b/drivers/infiniband/hw/ipath/ipath_rc.c index a08654042c0..52caa2edf5a 100644 --- a/drivers/infiniband/hw/ipath/ipath_rc.c +++ b/drivers/infiniband/hw/ipath/ipath_rc.c @@ -201,6 +201,18 @@ int ipath_make_rc_req(struct ipath_qp *qp, qp->s_rnr_timeout) goto done; + /* Limit the number of packets sent without an ACK. */ + if (ipath_cmp24(qp->s_psn, qp->s_last_psn + IPATH_PSN_CREDIT) > 0) { + qp->s_wait_credit = 1; + dev->n_rc_stalls++; + spin_lock(&dev->pending_lock); + if (list_empty(&qp->timerwait)) + list_add_tail(&qp->timerwait, + &dev->pending[dev->pending_index]); + spin_unlock(&dev->pending_lock); + goto done; + } + /* header size in 32-bit words LRH+BTH = (8+12)/4. */ hwords = 5; bth0 = 0; @@ -221,7 +233,7 @@ int ipath_make_rc_req(struct ipath_qp *qp, /* Check if send work queue is empty. */ if (qp->s_tail == qp->s_head) goto done; - qp->s_psn = wqe->psn = qp->s_next_psn; + wqe->psn = qp->s_next_psn; newreq = 1; } /* @@ -393,12 +405,6 @@ int ipath_make_rc_req(struct ipath_qp *qp, ss = &qp->s_sge; len = qp->s_len; if (len > pmtu) { - /* - * Request an ACK every 1/2 MB to avoid retransmit - * timeouts. - */ - if (((wqe->length - len) % (512 * 1024)) == 0) - bth2 |= 1 << 31; len = pmtu; break; } @@ -435,12 +441,6 @@ int ipath_make_rc_req(struct ipath_qp *qp, ss = &qp->s_sge; len = qp->s_len; if (len > pmtu) { - /* - * Request an ACK every 1/2 MB to avoid retransmit - * timeouts. - */ - if (((wqe->length - len) % (512 * 1024)) == 0) - bth2 |= 1 << 31; len = pmtu; break; } @@ -498,6 +498,8 @@ int ipath_make_rc_req(struct ipath_qp *qp, */ goto done; } + if (ipath_cmp24(qp->s_psn, qp->s_last_psn + IPATH_PSN_CREDIT - 1) >= 0) + bth2 |= 1 << 31; /* Request ACK. */ qp->s_len -= len; qp->s_hdrwords = hwords; qp->s_cur_sge = ss; @@ -737,6 +739,15 @@ bail: return; } +static inline void update_last_psn(struct ipath_qp *qp, u32 psn) +{ + if (qp->s_wait_credit) { + qp->s_wait_credit = 0; + tasklet_hi_schedule(&qp->s_task); + } + qp->s_last_psn = psn; +} + /** * do_rc_ack - process an incoming RC ACK * @qp: the QP the ACK came in on @@ -805,7 +816,7 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode) * The last valid PSN seen is the previous * request's. */ - qp->s_last_psn = wqe->psn - 1; + update_last_psn(qp, wqe->psn - 1); /* Retry this request. */ ipath_restart_rc(qp, wqe->psn, &wc); /* @@ -864,7 +875,7 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode) ipath_get_credit(qp, aeth); qp->s_rnr_retry = qp->s_rnr_retry_cnt; qp->s_retry = qp->s_retry_cnt; - qp->s_last_psn = psn; + update_last_psn(qp, psn); ret = 1; goto bail; @@ -883,7 +894,7 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode) goto bail; /* The last valid PSN is the previous PSN. */ - qp->s_last_psn = psn - 1; + update_last_psn(qp, psn - 1); dev->n_rc_resends += (int)qp->s_psn - (int)psn; @@ -898,7 +909,7 @@ static int do_rc_ack(struct ipath_qp *qp, u32 aeth, u32 psn, int opcode) case 3: /* NAK */ /* The last valid PSN seen is the previous request's. */ if (qp->s_last != qp->s_tail) - qp->s_last_psn = wqe->psn - 1; + update_last_psn(qp, wqe->psn - 1); switch ((aeth >> IPATH_AETH_CREDIT_SHIFT) & IPATH_AETH_CREDIT_MASK) { case 0: /* PSN sequence error */ @@ -1071,7 +1082,7 @@ static inline void ipath_rc_rcv_resp(struct ipath_ibdev *dev, * since we don't want s_sge modified. */ qp->s_len -= pmtu; - qp->s_last_psn = psn; + update_last_psn(qp, psn); spin_unlock_irqrestore(&qp->s_lock, flags); ipath_copy_sge(&qp->s_sge, data, pmtu); goto bail; -- cgit v1.2.3