Michael,
You can try this. The 3.10.0 code looked a little different, but this is the
gist of what I did on the older code. This is untested, so you are on the
hook for that part. I don't even know if this compiles, but it should:
--- linux-3.10.old/net/core/dev.c 2016-03-15 10:57:11.399668975 -0600
+++ linux-3.10/net/core/dev.c 2016-03-15 11:14:58.566734817 -0600
@@ -2675,28 +2675,6 @@
if (unlikely(test_bit(__QDISC_STATE_DEACTIVATED, &q->state))) {
kfree_skb(skb);
rc = NET_XMIT_DROP;
- } else if ((q->flags & TCQ_F_CAN_BYPASS) && !qdisc_qlen(q) &&
- qdisc_run_begin(q)) {
- /*
- * This is a work-conserving queue; there are no old skbs
- * waiting to be sent out; and the qdisc is not running -
- * xmit the skb directly.
- */
- if (!(dev->priv_flags & IFF_XMIT_DST_RELEASE))
- skb_dst_force(skb);
-
- qdisc_bstats_update(q, skb);
-
- if (sch_direct_xmit(skb, q, dev, txq, root_lock)) {
- if (unlikely(contended)) {
- spin_unlock(&q->busylock);
- contended = false;
- }
- __qdisc_run(q);
- } else
- qdisc_run_end(q);
-
- rc = NET_XMIT_SUCCESS;
} else {
skb_dst_force(skb);
rc = q->enqueue(skb, q) & NET_XMIT_MASK;
@@ -2705,7 +2683,8 @@
spin_unlock(&q->busylock);
contended = false;
}
- __qdisc_run(q);
+ __netif_schedule(q);
+ qdisc_run_end(q);
}
}
spin_unlock(root_lock);
Dave
-----Original Message-----
From: linux-rt-users-owner@xxxxxxxxxxxxxxx
[mailto:linux-rt-users-owner@xxxxxxxxxxxxxxx] On Behalf Of Stanislav Meduna
Sent: Tuesday, March 15, 2016 2:56 AM
To: Michael Hewitt; linux-rt-users@xxxxxxxxxxxxxxx
Subject: Re: Eliminating Packet Latency
On 3/14/2016 10:02 PM, Michael Hewitt wrote:
> Generally, we see packet delivery variations of less than 100
> microseconds, which is fabulous. Occasionally, we see a packet
> delivery delay in excess of 1000 microseconds.
Maybe this thread applies
http://www.spinics.net/lists/linux-rt-users/msg09887.html
(no straightforward solution there though).
--
Stano
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