From: Jamal Hadi Salim <jhs@mojatatu•com>
To: Alexei Starovoitov <ast@plumgrid•com>,
"David S. Miller" <davem@davemloft•net>
Cc: Eric Dumazet <edumazet@google•com>,
Daniel Borkmann <daniel@iogearbox•net>,
netdev@vger•kernel.org
Subject: Re: [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2 for ingress and egress
Date: Fri, 05 Jun 2015 06:03:15 -0400 [thread overview]
Message-ID: <557173E3.5020807@mojatatu.com> (raw)
In-Reply-To: <1433437914-15808-1-git-send-email-ast@plumgrid.com>
On 06/04/15 13:11, Alexei Starovoitov wrote:
> eBPF programs attached to ingress and egress qdiscs see inconsistent skb->data.
> For ingress L2 header is already pulled, whereas for egress it's present.
> This is known to program writers which are currently forced to use
> BPF_LL_OFF workaround.
> Since programs don't change skb internal pointers it is safe to do
> pull/push right around invocation of the program and earlier taps and
> later pt->func() will not be affected.
> Multiple taps via packet_rcv(), tpacket_rcv() are doing the same trick
> around run_filter/BPF_PROG_RUN even if skb_shared.
>
> This fix finally allows programs to use optimized LD_ABS/IND instructions
> without BPF_LL_OFF for higher performance.
> tc ingress + cls_bpf + samples/bpf/tcbpf1_kern.o
> w/o JIT w/JIT
> before 20.5 23.6 Mpps
> after 21.8 26.6 Mpps
>
> Old programs with BPF_LL_OFF will still work as-is.
>
> We can now undo most of the earlier workaround commit:
> a166151cbe33 ("bpf: fix bpf helpers to use skb->mac_header relative offsets")
>
> Signed-off-by: Alexei Starovoitov <ast@plumgrid•com>
> ---
Acked-by: Jamal Hadi Salim <jhs@mojatatu•com>
cheers,
jamal
next prev parent reply other threads:[~2015-06-05 10:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-04 17:11 [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2 for ingress and egress Alexei Starovoitov
2015-06-04 17:11 ` [PATCH v2 net-next 2/2] bpf: allow programs to write to certain skb fields Alexei Starovoitov
2015-06-07 9:01 ` David Miller
2015-06-05 10:03 ` Jamal Hadi Salim [this message]
2015-06-07 9:01 ` [PATCH v2 net-next 1/2] bpf: make programs see skb->data == L2 for ingress and egress David Miller
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