[PATCH net-next 04/10] net_sched: use qdisc_skb_cb(skb)->pkt_segs in bstats_update()
From: Eric Dumazet <edumazet@google.com>
Date: 2025-11-10 09:45:28
Subsystem:
cake qdisc, cbs/etf/taprio qdiscs, netem network emulator, networking [general], tc subsystem, the rest · Maintainers:
Toke Høiland-Jørgensen, Vinicius Costa Gomes, Stephen Hemminger, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jamal Hadi Salim, Jiri Pirko, Linus Torvalds
Avoid up to two cache line misses in qdisc dequeue() to fetch skb_shinfo(skb)->gso_segs/gso_size while qdisc spinlock is held. This gives a 5 % improvement in a TX intensive workload. Signed-off-by: Eric Dumazet <edumazet@google.com> --- include/net/sch_generic.h | 13 ++++++++++--- net/sched/sch_cake.c | 1 + net/sched/sch_dualpi2.c | 1 + net/sched/sch_netem.c | 1 + net/sched/sch_qfq.c | 2 +- net/sched/sch_taprio.c | 1 + net/sched/sch_tbf.c | 1 + 7 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 9cd8b5d4b23698fd8959ef40c303468e31c1d4af..ae037e56088208ad17f664c43689aee895569cab 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h@@ -829,6 +829,15 @@ static inline unsigned int qdisc_pkt_len(const struct sk_buff *skb) return qdisc_skb_cb(skb)->pkt_len; } +static inline unsigned int qdisc_pkt_segs(const struct sk_buff *skb) +{ + u32 pkt_segs = qdisc_skb_cb(skb)->pkt_segs; + + DEBUG_NET_WARN_ON_ONCE(pkt_segs != + skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1); + return pkt_segs; +} + /* additional qdisc xmit flags (NET_XMIT_MASK in linux/netdevice.h) */ enum net_xmit_qdisc_t { __NET_XMIT_STOLEN = 0x00010000,
@@ -870,9 +879,7 @@ static inline void _bstats_update(struct gnet_stats_basic_sync *bstats, static inline void bstats_update(struct gnet_stats_basic_sync *bstats, const struct sk_buff *skb) { - _bstats_update(bstats, - qdisc_pkt_len(skb), - skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1); + _bstats_update(bstats, qdisc_pkt_len(skb), qdisc_pkt_segs(skb)); } static inline void qdisc_bstats_cpu_update(struct Qdisc *sch,
diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 32bacfc314c260dccf94178d309ccb2be22d69e4..993ce808230fb7d4769c926f6c8368d927f5a45f 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c@@ -1800,6 +1800,7 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, skb_list_walk_safe(segs, segs, nskb) { skb_mark_not_on_list(segs); qdisc_skb_cb(segs)->pkt_len = segs->len; + qdisc_skb_cb(segs)->pkt_segs = 1; cobalt_set_enqueue_time(segs, now); get_cobalt_cb(segs)->adjusted_len = cake_overhead(q, segs);
diff --git a/net/sched/sch_dualpi2.c b/net/sched/sch_dualpi2.c
index 4b975feb52b1f3d3b37b31713d1477de5f5806d9..6d7e6389758dc8e645b1116efe4e11fb7290ac86 100644
--- a/net/sched/sch_dualpi2.c
+++ b/net/sched/sch_dualpi2.c@@ -475,6 +475,7 @@ static int dualpi2_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch, * (3) Enqueue fragment & set ts in dualpi2_enqueue_skb */ qdisc_skb_cb(nskb)->pkt_len = nskb->len; + qdisc_skb_cb(nskb)->pkt_segs = 1; dualpi2_skb_cb(nskb)->classified = dualpi2_skb_cb(skb)->classified; dualpi2_skb_cb(nskb)->ect = dualpi2_skb_cb(skb)->ect;
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index eafc316ae319e3f8c23b0cb0c58fdf54be102213..32a5f33040461f3be952055c097b5f2fe760a858 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c@@ -429,6 +429,7 @@ static struct sk_buff *netem_segment(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff *segs; netdev_features_t features = netif_skb_features(skb); + qdisc_skb_cb(skb)->pkt_segs = 1; segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); if (IS_ERR_OR_NULL(segs)) {
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c
index 2255355e51d350eded4549c1584b60d4d9b00fff..d920f57dc6d7659c510a98956c6dd2ed9e5ee5b8 100644
--- a/net/sched/sch_qfq.c
+++ b/net/sched/sch_qfq.c@@ -1250,7 +1250,7 @@ static int qfq_enqueue(struct sk_buff *skb, struct Qdisc *sch, } } - gso_segs = skb_is_gso(skb) ? skb_shinfo(skb)->gso_segs : 1; + gso_segs = qdisc_pkt_segs(skb); err = qdisc_enqueue(skb, cl->qdisc, to_free); if (unlikely(err != NET_XMIT_SUCCESS)) { pr_debug("qfq_enqueue: enqueue failed %d\n", err);
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 39b735386996eb59712a1fc28f7bb903ec1b2220..300d577b328699eb42d2b829ecfc76464fd7b186 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c@@ -595,6 +595,7 @@ static int taprio_enqueue_segmented(struct sk_buff *skb, struct Qdisc *sch, skb_list_walk_safe(segs, segs, nskb) { skb_mark_not_on_list(segs); qdisc_skb_cb(segs)->pkt_len = segs->len; + qdisc_skb_cb(segs)->pkt_segs = 1; slen += segs->len; /* FIXME: we should be segmenting to a smaller size
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 4c977f049670a600eafd219c898e5f29597be2c1..f2340164f579a25431979e12ec3d23ab828edd16 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c@@ -221,6 +221,7 @@ static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch, skb_mark_not_on_list(segs); seg_len = segs->len; qdisc_skb_cb(segs)->pkt_len = seg_len; + qdisc_skb_cb(segs)->pkt_segs = 1; ret = qdisc_enqueue(segs, q->qdisc, to_free); if (ret != NET_XMIT_SUCCESS) { if (net_xmit_drop_count(ret))
--
2.51.2.1041.gc1ab5b90ca-goog