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Commit d0f2faf7 authored by Mike Marciniszyn's avatar Mike Marciniszyn Committed by Roland Dreier
Browse files

IB/qib: Precompute timeout jiffies to optimize latency 



A new field is added to qib_qp called timeout_jiffies. It is
initialized upon create and modify.

The field is now used instead of a computation based on qp->timeout.

Signed-off-by: default avatarMike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent af061a64

drivers/infiniband/hw/qib/qib_qp.c

+8 −1
Original line number Diff line number Diff line
@@ -801,8 +801,12 @@ int qib_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr, 
	if (attr_mask & IB_QP_MIN_RNR_TIMER)

		qp->r_min_rnr_timer = attr->min_rnr_timer;



	if (attr_mask & IB_QP_TIMEOUT)

	if (attr_mask & IB_QP_TIMEOUT) {

		qp->timeout = attr->timeout;

		qp->timeout_jiffies =

			usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /

				1000UL);

	}



	if (attr_mask & IB_QP_QKEY)

		qp->qkey = attr->qkey;
@@ -1034,6 +1038,9 @@ struct ib_qp *qib_create_qp(struct ib_pd *ibpd, 
			goto bail_swq;

		}

		RCU_INIT_POINTER(qp->next, NULL);

		qp->timeout_jiffies =

			usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /

				1000UL);

		if (init_attr->srq)

			sz = 0;

		else {

drivers/infiniband/hw/qib/qib_rc.c

+2 −5
Original line number Diff line number Diff line
@@ -59,8 +59,7 @@ static void start_timer(struct qib_qp *qp) 
	qp->s_flags |= QIB_S_TIMER;

	qp->s_timer.function = rc_timeout;

	/* 4.096 usec. * (1 << qp->timeout) */

	qp->s_timer.expires = jiffies +

		usecs_to_jiffies((4096UL * (1UL << qp->timeout)) / 1000UL);

	qp->s_timer.expires = jiffies + qp->timeout_jiffies;

	add_timer(&qp->s_timer);

}
@@ -1519,9 +1518,7 @@ static void qib_rc_rcv_resp(struct qib_ibport *ibp, 
		 * 4.096 usec. * (1 << qp->timeout)

		 */

		qp->s_flags |= QIB_S_TIMER;

		mod_timer(&qp->s_timer, jiffies +

			usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /

					 1000UL));

		mod_timer(&qp->s_timer, jiffies + qp->timeout_jiffies);

		if (qp->s_flags & QIB_S_WAIT_ACK) {

			qp->s_flags &= ~QIB_S_WAIT_ACK;

			qib_schedule_send(qp);

drivers/infiniband/hw/qib/qib_verbs.h

+1 −0
Original line number Diff line number Diff line
@@ -496,6 +496,7 @@ struct qib_qp { 
	u32 s_last;             /* last completed entry */

	u32 s_ssn;              /* SSN of tail entry */

	u32 s_lsn;              /* limit sequence number (credit) */

	unsigned long timeout_jiffies;  /* computed from timeout */

	struct qib_swqe *s_wq;  /* send work queue */

	struct qib_swqe *s_wqe;

	struct qib_rq r_rq;             /* receive work queue */