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Commit 36ea63b5 authored by Sagi Grimberg's avatar Sagi Grimberg Committed by Nicholas Bellinger
Browse files

iser-target: Reduce CQ lock contention by batch polling 



In order to reduce the contention on CQ locking (present
in some LLDDs) we poll in batches of 16 work completion items.

Signed-off-by: default avatarSagi Grimberg <sagig@mellanox.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent 37d9fe80

drivers/infiniband/ulp/isert/ib_isert.c

+7 −5
Original line number Diff line number Diff line
@@ -2047,13 +2047,15 @@ isert_cq_work(struct work_struct *work) 
	enum { isert_poll_budget = 65536 };

	struct isert_comp *comp = container_of(work, struct isert_comp,

					       work);

	int completed = 0;

	struct ib_wc wc;

	struct ib_wc *const wcs = comp->wcs;

	int i, n, completed = 0;



	while (ib_poll_cq(comp->cq, 1, &wc) == 1) {

		isert_handle_wc(&wc);

	while ((n = ib_poll_cq(comp->cq, ARRAY_SIZE(comp->wcs), wcs)) > 0) {

		for (i = 0; i < n; i++)

			isert_handle_wc(&wcs[i]);



		if (++completed >= isert_poll_budget)

		completed += n;

		if (completed >= isert_poll_budget)

			break;

	}

drivers/infiniband/ulp/isert/ib_isert.h

+2 −0
Original line number Diff line number Diff line
@@ -165,6 +165,7 @@ struct isert_conn { 
 *

 * @device:     pointer to device handle

 * @cq:         completion queue

 * @wcs:        work completion array

 * @active_qps: Number of active QPs attached

 *              to completion context

 * @work:       completion work handle
@@ -172,6 +173,7 @@ struct isert_conn { 
struct isert_comp {

	struct isert_device     *device;

	struct ib_cq		*cq;

	struct ib_wc		 wcs[16];

	int                      active_qps;

	struct work_struct	 work;

};