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Commit 136d0711 authored by Tianyi Gou's avatar Tianyi Gou Committed by Gerrit - the friendly Code Review server
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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.

Change-Id: Ic5fe3faf86f177300d3018b9f60974ba3811641c
CRs-Fixed: 355156
Acked-by: default avatarJimi Shah <jimis@qualcomm.com>
Signed-off-by: default avatarTianyi Gou <tgou@codeaurora.org>
parent 35afb780

net/sched/sch_prio.c

+13 −1
Original line number Diff line number Diff line
@@ -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>
@@ -178,6 +179,7 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt) 
	struct prio_sched_data *q = qdisc_priv(sch);

	struct tc_prio_qopt *qopt;

	int i;

	int flow_change = 0;



	if (nla_len(opt) < sizeof(*qopt))

		return -EINVAL;
@@ -192,7 +194,10 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt) 
	}



	sch_tree_lock(sch);

	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);
@@ -227,6 +232,13 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt) 
			}

		}

	}



	/* 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;

}