From: Alexander Lobakin <aleksander.lobakin@intel.com>
To: Jakub Kicinski <kuba@kernel.org>
Cc: Larysa Zaremba <larysa.zaremba@intel.com>,
bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
sdf@google.com, haoluo@google.com, jolsa@kernel.org,
David Ahern <dsahern@gmail.com>,
Willem de Bruijn <willemb@google.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
Anatoly Burakov <anatoly.burakov@intel.com>,
Alexander Lobakin <alexandr.lobakin@intel.com>,
Magnus Karlsson <magnus.karlsson@gmail.com>,
Maryam Tahhan <mtahhan@redhat.com>,
xdp-hints@xdp-project.net, netdev@vger.kernel.org,
Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Simon Horman <simon.horman@corigine.com>,
Tariq Toukan <tariqt@mellanox.com>,
Saeed Mahameed <saeedm@mellanox.com>,
Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Subject: [xdp-hints] Re: [RFC bpf-next v2 09/24] xdp: Add VLAN tag hint
Date: Thu, 5 Oct 2023 18:58:33 +0200 [thread overview]
Message-ID: <e4bbe997-326f-b6cf-b6d6-f0a24f5aef39@intel.com> (raw)
In-Reply-To: <20231004110850.5501cd52@kernel.org>
From: Jakub Kicinski <kuba@kernel.org>
Date: Wed, 4 Oct 2023 11:08:50 -0700
> On Tue, 3 Oct 2023 15:09:39 +0200 Alexander Lobakin wrote:
>>> Sorry for a random chime-in but was there any discussion about
>>> the validity of VLAN stripping as an offload?
>>>
>>> I always thought this is a legacy "Windows" thing which allowed
>>> Windows drivers to operate on VLAN-tagged networks even before
>>> the OS itself understood VLANs... Do people actually care about
>>> having it enabled?
>>
>> On MIPS routers, I actually have some perf gains from having it enabled.
>> So they do, I'd say. Mediatek even has DSA tag stripping. Both save you
>> some skb->data push-pulls, csum corrections when CHECKSUM_COMPLETE, skb
>> unsharing in some cases, reduce L3/L4 headers cacheline spanning etc.
>
> No unsharing - you can still strip it in the driver.
Nobody manually strips VLAN tags in the drivers. You either have HW
stripping or pass VLAN-tagged skb to the stack, so that skb_vlan_untag()
takes care of it.
> Do you really think that for XDP kfunc call will be cheaper?
Wait, you initially asked:
* discussion about the validity of VLAN stripping as an offload?
* Do people actually care about having it enabled?
I did read this as "do we still need HW VLAN stripping in general?", not
only for XDP. So I replied for "in general" -- yes.
Forcefully disabling stripping when XDP is active is obscure IMO, let
the user decide.
Thanks,
Olek
next prev parent reply other threads:[~2023-10-05 17:00 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-27 7:51 [xdp-hints] [RFC bpf-next v2 00/24] XDP metadata via kfuncs for ice + mlx5 Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 01/24] ice: make RX hash reading code more reusable Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 02/24] ice: make RX HW timestamp " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 03/24] ice: make RX checksum checking " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 04/24] ice: Make ptype internal to descriptor info processing Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 05/24] ice: Introduce ice_xdp_buff Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 06/24] ice: Support HW timestamp hint Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 07/24] ice: Support RX hash XDP hint Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 08/24] ice: Support XDP hints in AF_XDP ZC mode Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 09/24] xdp: Add VLAN tag hint Larysa Zaremba
2023-10-03 12:35 ` [xdp-hints] " Jakub Kicinski
2023-10-03 13:09 ` Alexander Lobakin
2023-10-04 18:08 ` Jakub Kicinski
2023-10-05 16:58 ` Alexander Lobakin [this message]
2023-10-05 17:16 ` Jakub Kicinski
2023-10-05 17:20 ` David Ahern
2023-10-05 18:06 ` Jakub Kicinski
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 10/24] ice: Implement " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 11/24] ice: use VLAN proto from ring packet context in skb path Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 12/24] xdp: Add checksum hint Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 13/24] ice: Implement " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 14/24] ice: put XDP meta sources assignment under a static key condition Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 15/24] selftests/bpf: Allow VLAN packets in xdp_hw_metadata Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 16/24] net, xdp: allow metadata > 32 Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 17/24] selftests/bpf: Add flags and new hints to xdp_hw_metadata Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 18/24] veth: Implement VLAN tag and checksum XDP hint Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 19/24] net: make vlan_get_tag() return -ENODATA instead of -EINVAL Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 20/24] selftests/bpf: Use AF_INET for TX in xdp_metadata Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 21/24] selftests/bpf: Check VLAN tag and proto " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 22/24] selftests/bpf: check checksum state " Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 23/24] mlx5: implement VLAN tag XDP hint Larysa Zaremba
2023-09-27 7:51 ` [xdp-hints] [RFC bpf-next v2 24/24] mlx5: implement RX checksum " Larysa Zaremba
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