From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Daniel Borkmann <daniel@iogearbox.net>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
Jesper Dangaard Brouer <brouer@redhat.com>
Cc: alardam@gmail.com, magnus.karlsson@intel.com,
bjorn.topel@intel.com, andrii.nakryiko@gmail.com,
kuba@kernel.org, ast@kernel.org, netdev@vger.kernel.org,
davem@davemloft.net, john.fastabend@gmail.com, hawk@kernel.org,
jonathan.lemon@gmail.com, bpf@vger.kernel.org,
jeffrey.t.kirsher@intel.com, maciejromanfijalkowski@gmail.com,
intel-wired-lan@lists.osuosl.org,
Marek Majtyka <marekx.majtyka@intel.com>
Subject: Re: [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set
Date: Mon, 07 Dec 2020 13:03:28 +0100 [thread overview]
Message-ID: <87wnxt6cxb.fsf@toke.dk> (raw)
In-Reply-To: <eb305a4f-c189-6b32-f718-6e709ef0fa55@iogearbox.net>
Daniel Borkmann <daniel@iogearbox.net> writes:
> On 12/4/20 6:20 PM, Toke Høiland-Jørgensen wrote:
>> Daniel Borkmann <daniel@iogearbox.net> writes:
> [...]
>>> We tried to standardize on a minimum guaranteed amount, but unfortunately not
>>> everyone seems to implement it, but I think it would be very useful to query
>>> this from application side, for example, consider that an app inserts a BPF
>>> prog at XDP doing custom encap shortly before XDP_TX so it would be useful to
>>> know which of the different encaps it implements are realistically possible on
>>> the underlying XDP supported dev.
>>
>> How many distinct values are there in reality? Enough to express this in
>> a few flags (XDP_HEADROOM_128, XDP_HEADROOM_192, etc?), or does it need
>> an additional field to get the exact value? If we implement the latter
>> we also run the risk of people actually implementing all sorts of weird
>> values, whereas if we constrain it to a few distinct values it's easier
>> to push back against adding new values (as it'll be obvious from the
>> addition of new flags).
>
> It's not everywhere straight forward to determine unfortunately, see also [0,1]
> as some data points where Jesper looked into in the past, so in some cases it
> might differ depending on the build/runtime config..
>
> [0] https://lore.kernel.org/bpf/158945314698.97035.5286827951225578467.stgit@firesoul/
> [1] https://lore.kernel.org/bpf/158945346494.97035.12809400414566061815.stgit@firesoul/
Right, well in that case maybe we should just expose the actual headroom
as a separate netlink attribute? Although I suppose that would require
another round of driver changes since Jesper's patch you linked above
only puts this into xdp_buff at XDP program runtime.
Jesper, WDYT?
-Toke
next prev parent reply other threads:[~2020-12-07 12:05 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-04 10:28 [PATCH v2 bpf 0/5] New netdev feature flags for XDP alardam
2020-12-04 10:28 ` [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set alardam
2020-12-04 12:18 ` Toke Høiland-Jørgensen
2020-12-04 12:46 ` Maciej Fijalkowski
2020-12-04 15:21 ` Daniel Borkmann
2020-12-04 17:20 ` Toke Høiland-Jørgensen
2020-12-04 22:19 ` Daniel Borkmann
2020-12-07 11:54 ` Jesper Dangaard Brouer
2020-12-07 12:08 ` Toke Høiland-Jørgensen
2020-12-07 12:03 ` Toke Høiland-Jørgensen [this message]
2020-12-07 12:54 ` Jesper Dangaard Brouer
2020-12-07 20:52 ` John Fastabend
2020-12-07 22:38 ` Saeed Mahameed
2020-12-07 23:07 ` Maciej Fijalkowski
2020-12-09 6:03 ` John Fastabend
2020-12-09 9:54 ` Maciej Fijalkowski
2020-12-09 11:52 ` Jesper Dangaard Brouer
2020-12-09 15:41 ` David Ahern
2020-12-09 17:15 ` Saeed Mahameed
2020-12-10 3:34 ` David Ahern
2020-12-10 6:48 ` Saeed Mahameed
2020-12-10 15:30 ` David Ahern
2020-12-10 18:58 ` Saeed Mahameed
2021-01-05 11:56 ` Marek Majtyka
2021-02-01 16:16 ` Toke Høiland-Jørgensen
2021-02-02 11:26 ` Marek Majtyka
2021-02-02 12:05 ` Toke Høiland-Jørgensen
2021-02-02 19:34 ` Jakub Kicinski
2021-02-03 12:50 ` Marek Majtyka
2021-02-03 17:02 ` Jakub Kicinski
2021-02-10 10:53 ` Toke Høiland-Jørgensen
2021-02-10 18:31 ` Jakub Kicinski
2021-02-10 22:52 ` Toke Høiland-Jørgensen
2021-02-12 1:26 ` Jakub Kicinski
2021-02-12 2:05 ` Alexei Starovoitov
2021-02-12 7:02 ` Marek Majtyka
2021-02-16 14:30 ` Toke Høiland-Jørgensen
2020-12-09 15:44 ` David Ahern
2020-12-10 13:32 ` Explaining XDP redirect bulk size design (Was: [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set) Jesper Dangaard Brouer
2020-12-10 14:14 ` [Intel-wired-lan] " Magnus Karlsson
2020-12-10 17:30 ` Jesper Dangaard Brouer
2020-12-10 19:20 ` Saeed Mahameed
2020-12-08 1:01 ` [PATCH v2 bpf 1/5] net: ethtool: add xdp properties flag set David Ahern
2020-12-08 8:28 ` Jesper Dangaard Brouer
2020-12-08 11:58 ` Toke Høiland-Jørgensen
2020-12-09 5:50 ` John Fastabend
2020-12-09 10:26 ` Toke Høiland-Jørgensen
2020-12-08 9:00 ` Jesper Dangaard Brouer
2020-12-08 9:42 ` Daniel Borkmann
2020-12-04 12:57 ` Maciej Fijalkowski
2020-12-04 10:28 ` [PATCH v2 bpf 2/5] drivers/net: turn XDP properties on alardam
2020-12-04 12:19 ` Toke Høiland-Jørgensen
2020-12-04 10:28 ` [PATCH v2 bpf 3/5] xsk: add usage of xdp properties flags alardam
2020-12-04 10:29 ` [PATCH v2 bpf 4/5] xsk: add check for full support of XDP in bind alardam
2020-12-04 10:29 ` [PATCH v2 bpf 5/5] ethtool: provide xdp info with XDP_PROPERTIES_GET alardam
2020-12-04 17:20 ` [PATCH v2 bpf 0/5] New netdev feature flags for XDP Jakub Kicinski
2020-12-04 17:26 ` Toke Høiland-Jørgensen
2020-12-04 19:22 ` Jakub Kicinski
2020-12-07 12:04 ` Toke Høiland-Jørgensen
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