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Commit f07d1501 authored by Alexander Duyck's avatar Alexander Duyck Committed by David S. Miller
Browse files

multiq: Further multiqueue cleanup 



This patch resolves a few issues found with multiq including wording
suggestions and a problem seen in the allocation of queues.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 67333bb5

Documentation/networking/multiqueue.txt

+7 −7
Original line number Diff line number Diff line
@@ -29,15 +29,15 @@ Section 2: Qdisc support for multiqueue devices 


-----------------------------------------------



Currently two qdiscs support multiqueue devices.  The first is the default

pfifo_fast qdisc.  This qdisc supports one qdisc per hardware queue.  A new

round-robin qdisc, sch_multiq also supports multiple hardware queues. The

Currently two qdiscs are optimized for multiqueue devices.  The first is the

default pfifo_fast qdisc.  This qdisc supports one qdisc per hardware queue.

A new round-robin qdisc, sch_multiq also supports multiple hardware queues. The

qdisc is responsible for classifying the skb's and then directing the skb's to

bands and queues based on the value in skb->queue_mapping.  Use this field in

the base driver to determine which queue to send the skb to.



sch_multiq has been added for hardware that wishes to avoid unnecessary

requeuing.  It will cycle though the bands and verify that the hardware queue

sch_multiq has been added for hardware that wishes to avoid head-of-line

blocking.  It will cycle though the bands and verify that the hardware queue

associated with the band is not stopped prior to dequeuing a packet.



On qdisc load, the number of bands is based on the number of queues on the
@@ -63,8 +63,8 @@ band 1 => queue 1 
band 2 => queue 2

band 3 => queue 3



Traffic will begin flowing through each queue if your base device has either

the default simple_tx_hash or a custom netdev->select_queue() defined.

Traffic will begin flowing through each queue based on either the simple_tx_hash

function or based on netdev->select_queue() if you have it defined.



The behavior of tc filters remains the same.  However a new tc action,

skbedit, has been added.  Assuming you wanted to route all traffic to a

net/sched/sch_multiq.c

+9 −4
Original line number Diff line number Diff line
@@ -214,8 +214,8 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt) 
	sch_tree_lock(sch);

	q->bands = qopt->bands;

	for (i = q->bands; i < q->max_bands; i++) {

		if (q->queues[i] != &noop_qdisc) {

			struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);

		if (child != &noop_qdisc) {

			qdisc_tree_decrease_qlen(child, child->q.qlen);

			qdisc_destroy(child);

		}
@@ -250,7 +250,7 @@ static int multiq_tune(struct Qdisc *sch, struct nlattr *opt) 
static int multiq_init(struct Qdisc *sch, struct nlattr *opt)

{

	struct multiq_sched_data *q = qdisc_priv(sch);

	int i;

	int i, err;



	q->queues = NULL;
@@ -265,7 +265,12 @@ static int multiq_init(struct Qdisc *sch, struct nlattr *opt) 
	for (i = 0; i < q->max_bands; i++)

		q->queues[i] = &noop_qdisc;



	return multiq_tune(sch, opt);

	err = multiq_tune(sch,opt);



	if (err)

		kfree(q->queues);



	return err;

}



static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)