net: sched: Schedule PRIO qdisc when flow control released
The PRIO qdisc supports flow control, such that packet
dequeue can be disabled based on boolean flag 'enable_flow'.
When flow is re-enabled, the latency for new packets
arriving at network driver is high. To reduce the delay in
scheduling packets, the qdisc will now invoke
__netif_schedule() to expedite dequeue. This significantly
reduces the latency of packets arriving at network driver.
CRs-Fixed: 2085929
Change-Id: Ic5fe3faf86f177300d3018b9f60974ba3811641c
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index 353c6a1..230f7e9 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -18,6 +18,7 @@
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
+#include <linux/netdevice.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
@@ -164,6 +165,7 @@
struct Qdisc *queues[TCQ_PRIO_BANDS];
int oldbands = q->bands, i;
struct tc_prio_qopt *qopt;
+ int flow_change = 0;
if (nla_len(opt) < sizeof(*qopt))
return -EINVAL;
@@ -189,7 +191,10 @@
}
sch_tree_lock(sch);
- q->enable_flow = qopt->enable_flow;
+ if (q->enable_flow != qopt->enable_flow) {
+ q->enable_flow = qopt->enable_flow;
+ flow_change = 1;
+ }
q->bands = qopt->bands;
memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
@@ -205,6 +210,12 @@
q->queues[i] = queues[i];
sch_tree_unlock(sch);
+
+ /* Schedule qdisc when flow re-enabled */
+ if (flow_change && q->enable_flow) {
+ if (!test_bit(__QDISC_STATE_DEACTIVATED, &sch->state))
+ __netif_schedule(qdisc_root(sch));
+ }
return 0;
}