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authorSagi Grimberg <sagig@mellanox.com>2014-12-02 15:57:44 +0100
committerNicholas Bellinger <nab@linux-iscsi.org>2014-12-13 08:32:31 +0100
commit37d9fe80a3afc87a3d9f3d83aa0e6137f9fd7cde (patch)
treeb82fdaddb210cf6c69c9411014db8a705038dfe0
parentiser-target: Remove an atomic operation from the IO path (diff)
downloadlinux-37d9fe80a3afc87a3d9f3d83aa0e6137f9fd7cde.tar.xz
linux-37d9fe80a3afc87a3d9f3d83aa0e6137f9fd7cde.zip
iser-target: Introduce isert_poll_budget
In case the CQ is packed with completions, we can't just hog the CPU forever. Poll until a sufficient budget (currently hard-coded to 64k completions) and if budget is exhausted, bailout and give a chance to other threads. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
-rw-r--r--drivers/infiniband/ulp/isert/ib_isert.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index eb3d628ec4dd..22841487f600 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -2044,13 +2044,19 @@ isert_handle_wc(struct ib_wc *wc)
static void
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;
- while (ib_poll_cq(comp->cq, 1, &wc) == 1)
+ while (ib_poll_cq(comp->cq, 1, &wc) == 1) {
isert_handle_wc(&wc);
+ if (++completed >= isert_poll_budget)
+ break;
+ }
+
ib_req_notify_cq(comp->cq, IB_CQ_NEXT_COMP);
}