From: Kurt Kanzenbach <kurt@linutronix.de>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: brouer@redhat.com, Jesse Brandeburg <jesse.brandeburg@intel.com>,
Tony Nguyen <anthony.l.nguyen@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
John Fastabend <john.fastabend@gmail.com>,
Sven Auhagen <sven.auhagen@voleatech.de>,
intel-wired-lan@lists.osuosl.org, netdev@vger.kernel.org,
bpf@vger.kernel.org,
Ilias Apalodimas <ilias.apalodimas@linaro.org>,
Lorenzo Bianconi <lorenzo@kernel.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Alexander Duyck <alexander.duyck@gmail.com>
Subject: Re: [PATCH RFC net] igb: Fix XDP with PTP enabled
Date: Tue, 13 Apr 2021 09:34:49 +0200 [thread overview]
Message-ID: <874kga1vty.fsf@kurt> (raw)
In-Reply-To: <20210412162846.42706d99@carbon>
[-- Attachment #1: Type: text/plain, Size: 1086 bytes --]
On Mon Apr 12 2021, Jesper Dangaard Brouer wrote:
> On Mon, 12 Apr 2021 12:17:13 +0200
> Kurt Kanzenbach <kurt@linutronix.de> wrote:
>
>> When using native XDP with the igb driver, the XDP frame data doesn't point to
>> the beginning of the packet. It's off by 16 bytes. Everything works as expected
>> with XDP skb mode.
>>
>> Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
>> the timestamp before executing any XDP operations and adjust all other code
>> accordingly. The igc driver does it like that as well.
>
> (Cc. Alexander Duyck)
Thanks.
>
> Do we have enough room for the packet page-split tricks when these 16
> bytes are added?
I think so. AFAICT the timestamp header is accounted. There is
IGB_2K_TOO_SMALL_WITH_PADDING. If 2k isn't sufficient, then 3k buffers
are used.
The only thing this patch does, is adjusting the xdp->data pointer
before executing igb_run_xdp() instead of doing it afterwards. So, that
in the eBPF program `data' points to the packet data, and not to the
timestamp.
Thanks,
Kurt
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 832 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Kurt Kanzenbach <kurt@linutronix.de>
To: intel-wired-lan@osuosl.org
Subject: [Intel-wired-lan] [PATCH RFC net] igb: Fix XDP with PTP enabled
Date: Tue, 13 Apr 2021 09:34:49 +0200 [thread overview]
Message-ID: <874kga1vty.fsf@kurt> (raw)
In-Reply-To: <20210412162846.42706d99@carbon>
On Mon Apr 12 2021, Jesper Dangaard Brouer wrote:
> On Mon, 12 Apr 2021 12:17:13 +0200
> Kurt Kanzenbach <kurt@linutronix.de> wrote:
>
>> When using native XDP with the igb driver, the XDP frame data doesn't point to
>> the beginning of the packet. It's off by 16 bytes. Everything works as expected
>> with XDP skb mode.
>>
>> Actually these 16 bytes are used to store the packet timestamps. Therefore, pull
>> the timestamp before executing any XDP operations and adjust all other code
>> accordingly. The igc driver does it like that as well.
>
> (Cc. Alexander Duyck)
Thanks.
>
> Do we have enough room for the packet page-split tricks when these 16
> bytes are added?
I think so. AFAICT the timestamp header is accounted. There is
IGB_2K_TOO_SMALL_WITH_PADDING. If 2k isn't sufficient, then 3k buffers
are used.
The only thing this patch does, is adjusting the xdp->data pointer
before executing igb_run_xdp() instead of doing it afterwards. So, that
in the eBPF program `data' points to the packet data, and not to the
timestamp.
Thanks,
Kurt
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 832 bytes
Desc: not available
URL: <http://lists.osuosl.org/pipermail/intel-wired-lan/attachments/20210413/d36749d6/attachment.asc>
next prev parent reply other threads:[~2021-04-13 7:34 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-12 10:17 [PATCH RFC net] igb: Fix XDP with PTP enabled Kurt Kanzenbach
2021-04-12 10:17 ` [Intel-wired-lan] " Kurt Kanzenbach
2021-04-12 14:28 ` Jesper Dangaard Brouer
2021-04-12 14:28 ` [Intel-wired-lan] " Jesper Dangaard Brouer
2021-04-13 7:34 ` Kurt Kanzenbach [this message]
2021-04-13 7:34 ` Kurt Kanzenbach
2021-04-13 15:25 ` Alexander Duyck
2021-04-13 15:25 ` [Intel-wired-lan] " Alexander Duyck
2021-04-13 17:21 ` Kurt Kanzenbach
2021-04-13 17:21 ` [Intel-wired-lan] " Kurt Kanzenbach
2021-06-02 10:49 ` Penigalapati, Sandeep
2021-06-02 10:49 ` Penigalapati, Sandeep
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=874kga1vty.fsf@kurt \
--to=kurt@linutronix.de \
--cc=alexander.duyck@gmail.com \
--cc=anthony.l.nguyen@intel.com \
--cc=ast@kernel.org \
--cc=bigeasy@linutronix.de \
--cc=bpf@vger.kernel.org \
--cc=brouer@redhat.com \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=ilias.apalodimas@linaro.org \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=jesse.brandeburg@intel.com \
--cc=john.fastabend@gmail.com \
--cc=kuba@kernel.org \
--cc=lorenzo@kernel.org \
--cc=netdev@vger.kernel.org \
--cc=sven.auhagen@voleatech.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.