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qdisc: dequeue bulking also pickup GSO/TSO packets 

The TSO and GSO segmented packets already benefit from bulking
on their own.

The TSO packets have always taken advantage of the only updating
the tailptr once for a large packet.

The GSO segmented packets have recently taken advantage of
bulking xmit_more API, via merge commit 53fda7f7f9 ("Merge
branch 'xmit_list'"), specifically via commit 7f2e870f2a ("net:
Move main gso loop out of dev_hard_start_xmit() into helper.")
allowing qdisc requeue of remaining list.  And via commit
ce93718fb7 ("net: Don't keep around original SKB when we
software segment GSO frames.").

This patch allow further bulking of TSO/GSO packets together,
when dequeueing from the qdisc.

Testing:
 Measuring HoL (Head-of-Line) blocking for TSO and GSO, with
netperf-wrapper. Bulking several TSO show no performance regressions
(requeues were in the area 32 requeues/sec).

Bulking several GSOs does show small regression or very small
improvement (requeues were in the area 8000 requeues/sec).

 Using ixgbe 10Gbit/s with GSO bulking, we can measure some additional
latency. Base-case, which is "normal" GSO bulking, sees varying
high-prio queue delay between 0.38ms to 0.47ms.  Bulking several GSOs
together, result in a stable high-prio queue delay of 0.50ms.

 Using igb at 100Mbit/s with GSO bulking, shows an improvement.
Base-case sees varying high-prio queue delay between 2.23ms to 2.35ms

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesper Dangaard Brouer 2014-10-01 22:36:09 +02:00 committed by David S. Miller
parent 5772e9a346
commit 808e7ac0bd
1 changed files with 3 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
net/sched/sch_generic.c
View File

@ -63,10 +63,6 @@ static struct sk_buff *try_bulk_dequeue_skb(struct Qdisc *q,
struct sk_buff *skb, *tail_skb = head_skb;
while (bytelimit > 0) {
/* For now, don't bulk dequeue GSO (or GSO segmented) pkts */
if (tail_skb->next || skb_is_gso(tail_skb))
break;
skb = q->dequeue(q);
if (!skb)
break;
@ -76,11 +72,9 @@ static struct sk_buff *try_bulk_dequeue_skb(struct Qdisc *q,
if (!skb)
break;
/* "skb" can be a skb list after validate call above
* (GSO segmented), but it is okay to append it to
* current tail_skb->next, because next round will exit
* in-case "tail_skb->next" is a skb list.
*/
while (tail_skb->next) /* GSO list goto tail */
tail_skb = tail_skb->next;
tail_skb->next = skb;
tail_skb = skb;
}