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: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Sagi Grimberg 2014-12-02 16:57:45 +02:00 committed by Nicholas Bellinger
parent 37d9fe80a3
commit 36ea63b523
2 changed files with 9 additions and 5 deletions

View File

@ -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;
}

View File

@ -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;
};