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

Signed-off-by: Alexander Duyck <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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Alexander Duyck authored and davem330 committed Sep 13, 2008
1 parent 67333bb commit f07d150
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Showing 2 changed files with 16 additions and 11 deletions.
14 changes: 7 additions & 7 deletions Documentation/networking/multiqueue.txt
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
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13 changes: 9 additions & 4 deletions net/sched/sch_multiq.c
Original file line number Diff line number Diff line change
Expand Up @@ -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++) {
struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
if (child != &noop_qdisc) {
if (q->queues[i] != &noop_qdisc) {
struct Qdisc *child = xchg(&q->queues[i], &noop_qdisc);
qdisc_tree_decrease_qlen(child, child->q.qlen);
qdisc_destroy(child);
}
Expand Down Expand Up @@ -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;

Expand All @@ -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)
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