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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Thu, Feb 15, 2024 at 06:49:05PM CET, jhs@mojatatu.com wrote: >On Thu, Feb 15, 2024 at 11:06 AM Asbjørn Sloth Tønnesen wrote: >> >> TC filters come in 3 variants: >> - no flag (no opinion, process wherever possible) >> - skip_hw (do not process filter by hardware) >> - skip_sw (do not process filter by software) >> >> However skip_sw is implemented so that the skip_sw >> flag can first be checked, after it has been matched. >> >> IMHO it's common when using skip_sw, to use it on all rules. >> >> So if all filters in a block is skip_sw filters, then >> we can bail early, we can thus avoid having to match >> the filters, just to check for the skip_sw flag. >> >> +----------------------------+--------+--------+--------+ >> | Test description | Pre | Post | Rel. | >> | | kpps | kpps | chg. | >> +----------------------------+--------+--------+--------+ >> | basic forwarding + notrack | 1264.9 | 1277.7 | 1.01x | >> | switch to eswitch mode | 1067.1 | 1071.0 | 1.00x | >> | add ingress qdisc | 1056.0 | 1059.1 | 1.00x | >> +----------------------------+--------+--------+--------+ >> | 1 non-matching rule | 927.9 | 1057.1 | 1.14x | >> | 10 non-matching rules | 495.8 | 1055.6 | 2.13x | >> | 25 non-matching rules | 280.6 | 1053.5 | 3.75x | >> | 50 non-matching rules | 162.0 | 1055.7 | 6.52x | >> | 100 non-matching rules | 87.7 | 1019.0 | 11.62x | >> +----------------------------+--------+--------+--------+ >> >> perf top (100 n-m skip_sw rules - pre patch): >> 25.57% [kernel] [k] __skb_flow_dissect >> 20.77% [kernel] [k] rhashtable_jhash2 >> 14.26% [kernel] [k] fl_classify >> 13.28% [kernel] [k] fl_mask_lookup >> 6.38% [kernel] [k] memset_orig >> 3.22% [kernel] [k] tcf_classify >> >> perf top (100 n-m skip_sw rules - post patch): >> 4.28% [kernel] [k] __dev_queue_xmit >> 3.80% [kernel] [k] check_preemption_disabled >> 3.68% [kernel] [k] nft_do_chain >> 3.08% [kernel] [k] __netif_receive_skb_core.constprop.0 >> 2.59% [kernel] [k] mlx5e_xmit >> 2.48% [kernel] [k] mlx5e_skb_from_cqe_mpwrq_nonlinear >> > >The concept makes sense - but i am wondering when you have a mix of >skip_sw and skip_hw if it makes more sense to just avoid looking up >skip_sw at all in the s/w datapath? Potentially by separating the >hashes for skip_sw/hw. I know it's a deeper surgery - but would be Yeah, there could be 2 hashes: skip_sw/rest rest is the only one that needs to be looked-up in kernel datapath. skip_sw is just for control path. But is it worth the efford? I mean, since now, nobody seemed to care. If this patchset solves the problem for this usecase, I think it is enough. In that case, I'm fine with this patch: Reviewed-by: Jiri Pirko >more general purpose....unless i am missing something > >> Test setup: >> DUT: Intel Xeon D-1518 (2.20GHz) w/ Nvidia/Mellanox ConnectX-6 Dx 2x100G >> Data rate measured on switch (Extreme X690), and DUT connected as >> a router on a stick, with pktgen and pktsink as VLANs. >> Pktgen was in range 12.79 - 12.95 Mpps across all tests. >> > >Hrm. Those are "tiny" numbers (25G @64B is about 3x that). What are >the packet sizes? >Perhaps the traffic generator is a limitation here? >Also feels like you are doing exact matches? A sample flower rule >would have helped. > >cheers, >jamal >> Signed-off-by: Asbjørn Sloth Tønnesen >> --- >> include/net/pkt_cls.h | 5 +++++ >> net/core/dev.c | 3 +++ >> 2 files changed, 8 insertions(+) >> >> diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h >> index a4ee43f493bb..a065da4df7ff 100644 >> --- a/include/net/pkt_cls.h >> +++ b/include/net/pkt_cls.h >> @@ -74,6 +74,11 @@ static inline bool tcf_block_non_null_shared(struct tcf_block *block) >> return block && block->index; >> } >> >> +static inline bool tcf_block_has_skip_sw_only(struct tcf_block *block) >> +{ >> + return block && atomic_read(&block->filtercnt) == atomic_read(&block->skipswcnt); >> +} >> + >> static inline struct Qdisc *tcf_block_q(struct tcf_block *block) >> { >> WARN_ON(tcf_block_shared(block)); >> diff --git a/net/core/dev.c b/net/core/dev.c >> index d8dd293a7a27..7cd014e5066e 100644 >> --- a/net/core/dev.c >> +++ b/net/core/dev.c >> @@ -3910,6 +3910,9 @@ static int tc_run(struct tcx_entry *entry, struct sk_buff *skb, >> if (!miniq) >> return ret; >> >> + if (tcf_block_has_skip_sw_only(miniq->block)) >> + return ret; >> + >> tc_skb_cb(skb)->mru = 0; >> tc_skb_cb(skb)->post_ct = false; >> tcf_set_drop_reason(skb, *drop_reason); >> -- >> 2.43.0 >>