From: Jakub Kicinski <email@example.com>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Netdev <firstname.lastname@example.org>,
"Thomas Ptacek" <email@example.com>,
"Adhipati Blambangan" <firstname.lastname@example.org>,
"David Ahern" <email@example.com>,
"Toke Høiland-Jørgensen" <firstname.lastname@example.org>,
"Alexei Starovoitov" <email@example.com>
Subject: Re: [PATCH net v4] net: xdp: account for layer 3 packets in generic skb handler
Date: Fri, 14 Aug 2020 08:31:53 -0700 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
On Fri, 14 Aug 2020 08:56:48 +0200 Jason A. Donenfeld wrote:
> On Thu, Aug 13, 2020 at 11:01 PM Jakub Kicinski <email@example.com> wrote:
> > > I had originally dropped this patch, but the issue kept coming up in
> > > user reports, so here's a v4 of it. Testing of it is still rather slim,
> > > but hopefully that will change in the coming days.
> > Here an alternative patch, untested:
> Funny. But come on now... Why would we want to deprive our users of
> system consistency?
We should try for consistency between xdp and cls_bpf instead.
> Doesn't it make sense to allow users to use the same code across
> interfaces? You actually want them to rewrite their code to use a
> totally different trigger point just because of some weird kernel
> internals between interfaces?
We're not building an abstraction over the kernel stack so that users
won't have to worry how things work. Users need to have a minimal
understanding of how specific hooks integrate with the stack and what
they are for. And therefore why cls_bpf is actually more efficient to
use in L3 tunnel case.
> Why not make XDP more useful and more generic across interfaces? It's
> very common for systems to be receiving packets with a heavy ethernet
> card from the current data center, in addition to receiving packets
> from a tunnel interface connected to a remote data center, with a need
> to run the same XDP program on both interfaces. Why not support that
> kind of simplicity?
> This is _actually_ something that's come up _repeatedly_. This is a
> real world need from real users who are doing real things. Why not
> help them?
I'm sure it comes up repeatedly because we don't return any errors,
so people waste time investigating why it doesn't work.
> It's not at the expense of any formal consistency, or performance, or
> even semantic perfection. It costs very little to support these
> popular use cases.
next prev parent reply other threads:[~2020-08-14 15:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 19:58 [PATCH net v4] net: xdp: account for layer 3 packets in generic skb handler Jason A. Donenfeld
2020-08-13 21:01 ` Jakub Kicinski
2020-08-14 6:56 ` Jason A. Donenfeld
2020-08-14 7:30 ` [PATCH net v5] " Jason A. Donenfeld
2020-08-14 20:55 ` David Miller
2020-08-14 20:57 ` Jason A. Donenfeld
2020-08-15 7:41 ` [PATCH net v6] " Jason A. Donenfeld
2020-08-19 7:07 ` Jesper Dangaard Brouer
2020-08-19 23:22 ` David Miller
2020-08-20 9:13 ` Jason A. Donenfeld
2020-08-20 18:55 ` David Miller
2020-08-20 20:29 ` Jason A. Donenfeld
2020-08-14 15:31 ` Jakub Kicinski [this message]
2020-08-14 21:04 ` [PATCH net v4] " Jason A. Donenfeld
2020-08-14 21:26 ` David Miller
2020-08-15 7:54 ` Jason A. Donenfeld
2020-08-14 21:14 ` David Miller
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