From 808e7ac0bdef31204184904f6b3ea356a30a9ed5 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Wed, 1 Oct 2014 22:36:09 +0200 Subject: [PATCH] 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 53fda7f7f9e8 ("Merge branch 'xmit_list'"), specifically via commit 7f2e870f2a4 ("net: Move main gso loop out of dev_hard_start_xmit() into helper.") allowing qdisc requeue of remaining list. And via commit ce93718fb7cd ("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 --- net/sched/sch_generic.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-) diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c index c2e87e63b832..797ebef73642 100644 --- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -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; } -- 2.20.1