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[2a0c:4d80:42:443::2]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b7327a48bc7sm127747566b.71.2025.11.11.08.43.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 11 Nov 2025 08:43:41 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id A897C329611; Tue, 11 Nov 2025 17:43:40 +0100 (CET) From: Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , Jamal Hadi Salim , Cong Wang , Jiri Pirko , Kuniyuki Iwashima , Willem de Bruijn , netdev@vger.kernel.org, eric.dumazet@gmail.com, Eric Dumazet Subject: Re: [PATCH v2 net-next 00/14] net_sched: speedup qdisc dequeue In-Reply-To: <20251111093204.1432437-1-edumazet@google.com> References: <20251111093204.1432437-1-edumazet@google.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Tue, 11 Nov 2025 17:43:40 +0100 Message-ID: <87jyzwldtv.fsf@toke.dk> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Eric Dumazet writes: > Avoid up to two cache line misses in qdisc dequeue() to fetch > skb_shinfo(skb)->gso_segs/gso_size while qdisc spinlock is held. > > Idea is to cache gso_segs at enqueue time before spinlock is > acquired, in the first skb cache line, where we already > have qdisc_skb_cb(skb)->pkt_len. > > This series gives a 8 % improvement in a TX intensive workload. > > (120 Mpps -> 130 Mpps on a Turin host, IDPF with 32 TX queues) > > v2: - Fixed issues reported by Jakub (thanks !) > - Added three patches adding/using qdisc_dequeue_drop() after > recent regressions with CAKE qdisc reported by Toke. > More fixes to come later. > > v1: https://lore.kernel.org/netdev/20251110094505.3335073-1-edumazet@goog= le.com/T/#m8f562ed148f807c02fd02c6cd243604d449615b9 > > Eric Dumazet (14): > net_sched: make room for (struct qdisc_skb_cb)->pkt_segs > net: init shinfo->gso_segs from qdisc_pkt_len_init() > net_sched: initialize qdisc_skb_cb(skb)->pkt_segs in > qdisc_pkt_len_init() > net: use qdisc_pkt_len_segs_init() in sch_handle_ingress() > net_sched: use qdisc_skb_cb(skb)->pkt_segs in bstats_update() > net_sched: cake: use qdisc_pkt_segs() > net_sched: add Qdisc_read_mostly and Qdisc_write groups > net_sched: sch_fq: move qdisc_bstats_update() to fq_dequeue_skb() > net_sched: sch_fq: prefetch one skb ahead in dequeue() > net: prefech skb->priority in __dev_xmit_skb() > net: annotate a data-race in __dev_xmit_skb() > net_sched: add tcf_kfree_skb_list() helper > net_sched: add qdisc_dequeue_drop() helper > net_sched: use qdisc_dequeue_drop() in cake, codel, fq_codel As mentioned in the other thread[0], I tested this series and it definitely seems to improve things, so feel free to add my: Tested-by: Toke H=C3=B8iland-J=C3=B8rgensen