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linux/net/sched
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Toke Høiland-Jørgensen b0c19ed608 sch_cake: Take advantage of skb->hash where appropriate 
While the other fq-based qdiscs take advantage of skb->hash and doesn't
recompute it if it is already set, sch_cake does not.

This was a deliberate choice because sch_cake hashes various parts of the
packet header to support its advanced flow isolation modes. However,
foregoing the use of skb->hash entirely loses a few important benefits:

- When skb->hash is set by hardware, a few CPU cycles can be saved by not
  hashing again in software.

- Tunnel encapsulations will generally preserve the value of skb->hash from
  before the encapsulation, which allows flow-based qdiscs to distinguish
  between flows even though the outer packet header no longer has flow
  information.

It turns out that we can preserve these desirable properties in many cases,
while still supporting the advanced flow isolation properties of sch_cake.
This patch does so by reusing the skb->hash value as the flow_hash part of
the hashing procedure in cake_hash() only in the following conditions:

- If the skb->hash is marked as covering the flow headers (skb->l4_hash is
  set)

AND

- NAT header rewriting is either disabled, or did not change any values
  used for hashing. The latter is important to match local-origin packets
  such as those of a tunnel endpoint.

The immediate motivation for fixing this was the recent patch to WireGuard
to preserve the skb->hash on encapsulation. As such, this is also what I
tested against; with this patch, added latency under load for competing
flows drops from ~8 ms to sub-1ms on an RRUL test over a WireGuard tunnel
going through a virtual link shaped to 1Gbps using sch_cake. This matches
the results we saw with a similar setup using sch_fq_codel when testing the
WireGuard patch.

Fixes: 046f6fd5da ("sched: Add Common Applications Kept Enhanced (cake) qdisc")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-05-30 21:52:20 -07:00
..
act_api.c net: sched: implement terse dump support in act 2020-05-15 10:23:11 -07:00
act_bpf.c bpf: Add socket assign support 2020-03-30 13:45:04 -07:00
act_connmark.c net: sched: update action implementations to support flags 2019-10-30 18:07:51 -07:00
act_csum.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 15:42:43 -08:00
act_ct.c net/sched: act_ct: update nf_conn_acct for act_ct SW offload in flowtable 2020-04-22 12:48:17 -07:00
act_ctinfo.c net: sched: act_ctinfo: fix memory leak 2020-01-19 16:02:15 +01:00
act_gact.c net: sched: update action implementations to support flags 2019-10-30 18:07:51 -07:00
act_gate.c net: qos: introduce a gate control flow action 2020-05-01 16:08:19 -07:00
act_ife.c net/sched: act_ife: initalize ife->metalist earlier 2020-01-17 10:58:15 +01:00
act_ipt.c net: sched: update action implementations to support flags 2019-10-30 18:07:51 -07:00
act_meta_mark.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_meta_skbprio.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_meta_skbtcindex.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
act_mirred.c net: Fix CONFIG_NET_CLS_ACT=n and CONFIG_NFT_FWD_NETDEV={y, m} build 2020-03-25 12:24:33 -07:00
act_mpls.c net: Fixed updating of ethertype in skb_mpls_push() 2019-12-04 17:11:25 -08:00
act_nat.c icmp: remove duplicate code 2019-11-05 14:03:11 -08:00
act_pedit.c sched: act_pedit: Implement stats_update callback 2020-03-26 19:20:37 -07:00
act_police.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 15:42:43 -08:00
act_sample.c net: sched: lock action when translating it to flow_action infra 2020-02-17 14:17:02 -08:00
act_simple.c net_sched: extend packet counter to 64bit 2019-11-05 18:20:55 -08:00
act_skbedit.c sched: act_skbedit: Implement stats_update callback 2020-03-26 19:20:37 -07:00
act_skbmod.c net: sched: update action implementations to support flags 2019-10-30 18:07:51 -07:00
act_tunnel_key.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 15:42:43 -08:00
act_vlan.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 15:42:43 -08:00
cls_api.c net: sched: implement terse dump support in act 2020-05-15 10:23:11 -07:00
cls_basic.c net_sched: fix ops->bind_class() implementations 2020-01-27 10:51:43 +01:00
cls_bpf.c net_sched: fix ops->bind_class() implementations 2020-01-27 10:51:43 +01:00
cls_cgroup.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cls_flow.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cls_flower.c cls_flower: Support filtering on multiple MPLS Label Stack Entries 2020-05-26 15:22:58 -07:00
cls_fw.c net_sched: fix ops->bind_class() implementations 2020-01-27 10:51:43 +01:00
cls_matchall.c net: sched: expose HW stats types per action used by drivers 2020-03-30 11:06:49 -07:00
cls_route.c net_sched: cls_route: remove the right filter from hashtable 2020-03-16 01:59:32 -07:00
cls_rsvp6.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cls_rsvp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
cls_rsvp.h cls_rsvp: fix rsvp_policy 2020-02-01 12:25:06 -08:00
cls_tcindex.c net_sched: fix a missing refcnt in tcindex_init() 2020-04-03 16:00:08 -07:00
cls_u32.c net_sched: fix ops->bind_class() implementations 2020-01-27 10:51:43 +01:00
em_canid.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 11 2019-05-21 11:28:45 +02:00
em_cmp.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
em_ipset.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
em_ipt.c net: sched : Remove unnecessary cast in kfree 2020-04-23 15:50:50 -07:00
em_meta.c net: annotate lockless accesses to sk->sk_max_ack_backlog 2019-11-06 16:14:48 -08:00
em_nbyte.c net: sched: Replace zero-length array with flexible-array member 2020-02-29 21:27:02 -08:00
em_text.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
em_u32.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
ematch.c net_sched: ematch: reject invalid TCF_EM_SIMPLE 2020-01-27 10:55:26 +01:00
Kconfig net: qos: introduce a gate control flow action 2020-05-01 16:08:19 -07:00
Makefile net: qos: introduce a gate control flow action 2020-05-01 16:08:19 -07:00
sch_api.c net_sched: add a tracepoint for qdisc creation 2020-05-27 15:05:49 -07:00
sch_atm.c net: sched: Replace zero-length array with flexible-array member 2020-02-29 21:27:02 -08:00
sch_blackhole.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sch_cake.c sch_cake: Take advantage of skb->hash where appropriate 2020-05-30 21:52:20 -07:00
sch_cbq.c sch_cbq: validate TCA_CBQ_WRROPT to avoid crash 2019-09-30 11:07:46 -07:00
sch_cbs.c net: cbs: Fix software cbs to consider packet sending time 2020-03-24 16:14:05 -07:00
sch_choke.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-05-06 22:10:13 -07:00
sch_codel.c net: sched: Fix a possible null-pointer dereference in dequeue_func() 2019-07-29 09:46:58 -07:00
sch_drr.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
sch_dsmark.c sch_dsmark: fix potential NULL deref in dsmark_init() 2019-10-04 18:28:30 -07:00
sch_etf.c sched: etf: do not assume all sockets are full blown 2020-04-22 19:20:28 -07:00
sch_ets.c net: sch_ets: Make the ETS qdisc offloadable 2019-12-18 13:32:29 -08:00
sch_fifo.c net: sched: Make FIFO Qdisc offloadable 2020-03-05 14:03:31 -08:00
sch_fq_codel.c fq_codel: fix TCA_FQ_CODEL_DROP_BATCH_SIZE sanity checks 2020-04-27 11:34:04 -07:00
sch_fq_pie.c pie: remove pie_vars->accu_prob_overflows 2020-03-04 13:25:55 -08:00
sch_fq.c net_sched: sch_fq: add horizon attribute 2020-05-04 11:56:17 -07:00
sch_generic.c net_sched: get rid of unnecessary dev_qdisc_reset() 2020-05-27 15:05:49 -07:00
sch_gred.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sch_hfsc.c netlink: make validation more configurable for future strictness 2019-04-27 17:07:21 -04:00
sch_hhf.c net/flow_dissector: switch to siphash 2019-10-23 20:13:22 -07:00
sch_htb.c net: sched: sch_htb: don't call qdisc_put() while holding tree lock 2019-09-27 12:13:55 +02:00
sch_ingress.c net: sched: Pass ingress block to tcf_classify_ingress 2020-02-19 17:49:48 -08:00
sch_mq.c net: sched: fix dump qlen for sch_mq/sch_mqprio with NOLOCK subqueues 2019-12-03 11:53:55 -08:00
sch_mqprio.c mqprio: Fix out-of-bounds access in mqprio_dump 2019-12-06 11:58:45 -08:00
sch_multiq.c net: sched: fix tc -s class show no bstats on class with nolock subqueues 2019-11-30 10:38:40 -08:00
sch_netem.c net: sched: Replace zero-length array with flexible-array member 2020-02-29 21:27:02 -08:00
sch_pie.c net: sched: pie: change tc_pie_xstats->prob 2020-03-09 18:05:55 -07:00
sch_plug.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
sch_prio.c net: sch_prio: When ungrafting, replace with FIFO 2020-01-08 12:45:53 -08:00
sch_qfq.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
sch_red.c netlink: remove type-unsafe validation_data pointer 2020-04-30 17:51:41 -07:00
sch_sfb.c net/flow_dissector: switch to siphash 2019-10-23 20:13:22 -07:00
sch_sfq.c sch_sfq: validate silly quantum values 2020-04-27 11:49:57 -07:00
sch_skbprio.c net_sched: sch_skbprio: add message validation to skbprio_change() 2020-05-03 15:52:13 -07:00
sch_taprio.c taprio: Fix sending packets without dequeueing them 2020-03-12 11:25:08 -07:00
sch_tbf.c net: sched: Make TBF Qdisc offloadable 2020-01-25 10:56:31 +01:00
sch_teql.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00