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: Mike Marciniszyn <mike.marciniszyn@qlogic.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/drivers/infiniband/hw/qib/qib_qp.c b/drivers/infiniband/hw/qib/qib_qp.c
index 500981b..7e7e16f 100644
--- a/drivers/infiniband/hw/qib/qib_qp.c
+++ b/drivers/infiniband/hw/qib/qib_qp.c
@@ -801,8 +801,12 @@
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 @@
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 {
diff --git a/drivers/infiniband/hw/qib/qib_rc.c b/drivers/infiniband/hw/qib/qib_rc.c
index 5d77cb8..ecfa087 100644
--- a/drivers/infiniband/hw/qib/qib_rc.c
+++ b/drivers/infiniband/hw/qib/qib_rc.c
@@ -59,8 +59,7 @@
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 @@
* 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);
diff --git a/drivers/infiniband/hw/qib/qib_verbs.h b/drivers/infiniband/hw/qib/qib_verbs.h
index d7b6109..0c19ef0 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.h
+++ b/drivers/infiniband/hw/qib/qib_verbs.h
@@ -496,6 +496,7 @@
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 */