[PATCH] IB/qib: Improve ipoib UD performance

[PATCH] IB/qib: Improve ipoib UD performance

[Mike Marciniszyn]

Based on profiling, UD performance drops in case of processes
in a single client due to excess context switches when
the progress workqueue is scheduled.

This is solved by modifying the heuristic to select the
direct progress instead of the scheduling progress via
the workqueue when UD-like situations are detected in
the heuristic.

Reviewed-by: Vinit Agnihotri <vinit.abhay.agnihotri-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/infiniband/hw/qib/qib_verbs.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/infiniband/hw/qib/qib_verbs.c b/drivers/infiniband/hw/qib/qib_verbs.c
index de6cb6f..f29f097 100644
--- a/drivers/infiniband/hw/qib/qib_verbs.c
+++ b/drivers/infiniband/hw/qib/qib_verbs.c
@@ -346,6 +346,7 @@ static int qib_post_one_send(struct qib_qp *qp, struct ib_send_wr *wr,
 	unsigned long flags;
 	struct qib_lkey_table *rkt;
 	struct qib_pd *pd;
+	int avoid_schedule = 0;
 
 	spin_lock_irqsave(&qp->s_lock, flags);
 
@@ -438,11 +439,15 @@ static int qib_post_one_send(struct qib_qp *qp, struct ib_send_wr *wr,
 	    qp->ibqp.qp_type == IB_QPT_RC) {
 		if (wqe->length > 0x80000000U)
 			goto bail_inval_free;
+		if (wqe->length <= qp->pmtu)
+			avoid_schedule = 1;
 	} else if (wqe->length > (dd_from_ibdev(qp->ibqp.device)->pport +
-				  qp->port_num - 1)->ibmtu)
+				  qp->port_num - 1)->ibmtu) {
 		goto bail_inval_free;
-	else
+	} else {
 		atomic_inc(&to_iah(ud_wr(wr)->ah)->refcount);
+		avoid_schedule = 1;
+	}
 	wqe->ssn = qp->s_ssn++;
 	qp->s_head = next;
 
@@ -458,7 +463,7 @@ bail_inval_free:
 bail_inval:
 	ret = -EINVAL;
 bail:
-	if (!ret && !wr->next &&
+	if (!ret && !wr->next && !avoid_schedule &&
 	 !qib_sdma_empty(
 	   dd_from_ibdev(qp->ibqp.device)->pport + qp->port_num - 1)) {
 		qib_schedule_send(qp);

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Re: [PATCH] IB/qib: Improve ipoib UD performance

[Doug Ledford]

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On 12/24/2015 11:19 AM, Mike Marciniszyn wrote:
> Based on profiling, UD performance drops in case of processes
> in a single client due to excess context switches when
> the progress workqueue is scheduled.
> 
> This is solved by modifying the heuristic to select the
> direct progress instead of the scheduling progress via
> the workqueue when UD-like situations are detected in
> the heuristic.
> 
> Reviewed-by: Vinit Agnihotri <vinit.abhay.agnihotri-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
> Signed-off-by: Mike Marciniszyn <mike.marciniszyn-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>

Thanks, applied.


-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
              GPG KeyID: 0E572FDD



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