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IB/ipath: Limit # of packets sent without an ACK received

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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 <bryan.osullivan@qlogic.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
This commit is contained in:
Bryan O'Sullivan 2006-09-28 08:59:57 -07:00 committed by Roland Dreier
parent fd6a79a786
commit 6022943eb4
4 changed files with 37 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/infiniband/hw/ipath/ipath_qp.c
View File

@ -342,6 +342,7 @@ static void ipath_reset_qp(struct ipath_qp *qp)
qp->s_last = 0;
qp->s_ssn = 1;
qp->s_lsn = 0;
qp->s_wait_credit = 0;
if (qp->r_rq.wq) {
qp->r_rq.wq->head = 0;
qp->r_rq.wq->tail = 0;
@ -516,7 +517,7 @@ int ipath_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
qp->remote_qpn = attr->dest_qp_num;
if (attr_mask & IB_QP_SQ_PSN) {
qp->s_next_psn = attr->sq_psn;
qp->s_psn = qp->s_next_psn = attr->sq_psn;
qp->s_last_psn = qp->s_next_psn - 1;
}

47
drivers/infiniband/hw/ipath/ipath_rc.c
View File

@ -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;

3
drivers/infiniband/hw/ipath/ipath_verbs.c
View File

@ -1683,6 +1683,7 @@ static ssize_t show_stats(struct class_device *cdev, char *buf)
"RC OTH NAKs %d\n"
"RC timeouts %d\n"
"RC RDMA dup %d\n"
"RC stalls %d\n"
"piobuf wait %d\n"
"no piobuf %d\n"
"PKT drops %d\n"
@ -1690,7 +1691,7 @@ static ssize_t show_stats(struct class_device *cdev, char *buf)
dev->n_rc_resends, dev->n_rc_qacks, dev->n_rc_acks,
dev->n_seq_naks, dev->n_rdma_seq, dev->n_rnr_naks,
dev->n_other_naks, dev->n_timeouts,
dev->n_rdma_dup_busy, dev->n_piowait,
dev->n_rdma_dup_busy, dev->n_rc_stalls, dev->n_piowait,
dev->n_no_piobuf, dev->n_pkt_drops, dev->n_wqe_errs);
for (i = 0; i < ARRAY_SIZE(dev->opstats); i++) {
const struct ipath_opcode_stats *si = &dev->opstats[i];

4
drivers/infiniband/hw/ipath/ipath_verbs.h
View File

@ -370,6 +370,7 @@ struct ipath_qp {
u8 s_rnr_retry_cnt;
u8 s_retry; /* requester retry counter */
u8 s_rnr_retry; /* requester RNR retry counter */
u8 s_wait_credit; /* limit number of unacked packets sent */
u8 s_pkey_index; /* PKEY index to use */
u8 timeout; /* Timeout for this QP */
enum ib_mtu path_mtu;
@ -393,6 +394,8 @@ struct ipath_qp {
#define IPATH_S_BUSY 0
#define IPATH_S_SIGNAL_REQ_WR 1
#define IPATH_PSN_CREDIT 2048
/*
* Since struct ipath_swqe is not a fixed size, we can't simply index into
* struct ipath_qp.s_wq. This function does the array index computation.
@ -521,6 +524,7 @@ struct ipath_ibdev {
u32 n_rnr_naks;
u32 n_other_naks;
u32 n_timeouts;
u32 n_rc_stalls;
u32 n_pkt_drops;
u32 n_vl15_dropped;
u32 n_wqe_errs;