From: Jesper Dangaard Brouer <jbrouer@redhat.com>
To: "Jakub Kicinski" <kuba@kernel.org>,
"Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: brouer@redhat.com,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Zvi Effron <zeffron@riotgames.com>,
Lorenz Bauer <lmb@cloudflare.com>,
Lorenzo Bianconi <lbianconi@redhat.com>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Network Development <netdev@vger.kernel.org>,
bpf <bpf@vger.kernel.org>
Subject: Re: Redux: Backwards compatibility for XDP multi-buff
Date: Mon, 27 Sep 2021 14:43:56 +0200 [thread overview]
Message-ID: <7e47e065-f9b2-4b98-923d-94f5a9484a83@redhat.com> (raw)
In-Reply-To: <20210923064634.636ef48a@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
On 23/09/2021 15.46, Jakub Kicinski wrote:
> Let me make a general statement that we can't build large systems
> without division of responsibilities. Device specific logic has to
> be left to the driver. It's up to veth to apply its extra rules.
>
> As Zvi said, tho, this can be left for later. IMHO initial patches can
> drop all mb frames on redirect in the core, so we can make progress.
I agree that for *initial* patchset for REDIRECT (func calling
ndo_xdp_xmit) it can drop MB frames on redirect in the core, when the
drivers ndo_xdp_xmit doesn't support this.
BUT only so we can make progress.
As soon as possible (preferably in same kernel release) a follow-up
patchset should make a serious attempt at updating all drivers
ndo_xdp_xmit to support multi-buffer (MB).
As MB use the same/compatible layout as skb_shared_info, it should be a
fairly small effort to update drivers, for *transmitting* multi-buff. As
drivers already support this for normal SKBs.
It will be a larger effort to support XDP multi-buff on RX, as often the
RX-loop need to be adjusted/reordered to "delay" calling XDP-prog until
all fragments have been "collected". And MTU check adjusted.
This imply that the driver net_device xdp_features need two feature bits
for this MB feature.
IMHO it makes sense to detangle RX and TX, as IMHO we should allow MB
frames to be TX redirect out a driver that have an old non-MB aware
XDP-prog loaded.
--Jesper
next prev parent reply other threads:[~2021-09-27 12:44 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-21 16:06 Redux: Backwards compatibility for XDP multi-buff Toke Høiland-Jørgensen
2021-09-21 17:31 ` Zvi Effron
2021-09-21 18:22 ` Toke Høiland-Jørgensen
2021-09-21 19:17 ` Zvi Effron
2021-09-21 22:14 ` Toke Høiland-Jørgensen
2021-09-21 23:10 ` Zvi Effron
2021-09-22 20:13 ` Toke Høiland-Jørgensen
2021-09-21 20:12 ` Alexei Starovoitov
2021-09-21 22:20 ` Toke Høiland-Jørgensen
2021-09-21 22:51 ` Jakub Kicinski
2021-09-22 20:01 ` Toke Høiland-Jørgensen
2021-09-22 21:23 ` Zvi Effron
2021-09-23 18:45 ` Toke Høiland-Jørgensen
2021-09-23 13:46 ` Jakub Kicinski
2021-09-27 12:43 ` Jesper Dangaard Brouer [this message]
2021-09-21 22:54 ` Jakub Kicinski
2021-09-22 20:02 ` Toke Høiland-Jørgensen
2021-09-22 21:11 ` Zvi Effron
2021-09-23 19:00 ` Toke Høiland-Jørgensen
2021-09-23 10:33 ` Lorenz Bauer
2021-09-23 12:59 ` Toke Høiland-Jørgensen
2021-09-24 10:18 ` Lorenz Bauer
2021-09-24 17:55 ` Zvi Effron
2021-09-24 19:38 ` Toke Høiland-Jørgensen
2021-09-28 8:47 ` Lorenz Bauer
2021-09-28 13:43 ` Toke Høiland-Jørgensen
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