From: Alexei Starovoitov <ast@plumgrid•com>
To: Jamal Hadi Salim <jhs@mojatatu•com>, David Miller <davem@davemloft•net>
Cc: daniel@iogearbox•net, tgraf@suug•ch, jiri@resnulli•us,
netdev@vger•kernel.org
Subject: Re: [PATCH v3 net-next 2/2] tc: add 'needs_l2' flag to ingress qdisc
Date: Thu, 09 Apr 2015 10:03:28 -0700 [thread overview]
Message-ID: <5526B0E0.7060000@plumgrid.com> (raw)
In-Reply-To: <5526593E.4040608@mojatatu.com>
On 4/9/15 3:49 AM, Jamal Hadi Salim wrote:
> those devices and only speacial case with them. Your assumptions of
> blindly pushing/pulling will break in some cases (take a look at
> mirred).
you underestimated how much time I've spent studying mirred ;)
In particular my v2 patch fixes two bugs in it:
- it was forwarding packets with L2 present to tunnel devices if used
with egress qdisc
- it wasn't updating skb->csum with ingress qdisc
In v3 since 'needs_l2' is an optional flag, I didn't touch mirred
and left its bugs for the future patches.
> Your changes penalize everyone else because of this assumption
> bpf makes. We have always tried to be sensitive to perfomance.
hmm. penalize everyone? it's an optional flag.
If ingress_l2 is used with cls_bpf plus some other classifier,
sure, the other classifier is paying potential cost skb_share_check
if taps are active. The chances of having more than a couple classifiers
on a single device are very slim, since they're called sequentially
and killing performance regardless.
In most of the use cases I'm after, cls_bpf will be the only classifier
attached. In some cases there may be few others, but cls_bpf will be
the first and the heaviest one. So it makes sense to optimize for it.
> code path and you are adding a bunch more unconditionally.
not true at all. Looks like you misread the v3 patch completely.
It's an optional flag.
next prev parent reply other threads:[~2015-04-09 17:03 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-08 23:26 [PATCH v3 net-next 1/2] net: introduce skb_postpush_rcsum() helper Alexei Starovoitov
2015-04-08 23:26 ` [PATCH v3 net-next 2/2] tc: add 'needs_l2' flag to ingress qdisc Alexei Starovoitov
2015-04-09 2:44 ` David Miller
2015-04-09 3:05 ` Alexei Starovoitov
2015-04-09 3:14 ` David Miller
2015-04-09 3:39 ` Alexei Starovoitov
2015-04-09 5:20 ` Alexei Starovoitov
2015-04-09 5:25 ` David Miller
2015-04-09 15:15 ` Daniel Borkmann
2015-04-09 15:36 ` Eric Dumazet
2015-04-09 17:20 ` Alexei Starovoitov
2015-04-09 10:49 ` Jamal Hadi Salim
2015-04-09 11:02 ` Jamal Hadi Salim
2015-04-09 15:38 ` Daniel Borkmann
2015-04-10 11:49 ` Jamal Hadi Salim
2015-04-09 17:03 ` Alexei Starovoitov [this message]
2015-04-10 12:48 ` Jamal Hadi Salim
2015-04-10 22:35 ` Alexei Starovoitov
2015-04-13 14:28 ` Jamal Hadi Salim
2015-04-13 16:13 ` Alexei Starovoitov
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