Message-ID: <CADFiAcL-kAzpJJ+KAkvw2tH8H0-21kyOusPSPybcmkf3CM7w9g@mail.gmail.com>
Date:   Wed, 11 Oct 2023 14:25:55 +0900
From:   takeru hayasaka <hayatake396@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Jesse Brandeburg <jesse.brandeburg@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] ethtool: ice: Support for RSS settings to GTP
 from ethtool

Thank you for teaching me so much!

> > Sorry! My email was blocked because it wasn't sent in plain text mode.
> > I've made the necessary changes and will resend it.
I got it. I'll do it like that :)
Please let me know if I'm using it incorrectly.

> Makes sense, thanks for the extra information. I think it would be
> worth adding all of this to the commit message!

of course:)
I got it. I will add this background information when I issue a patch
for the next version.

> Regarding the patch - you are only adding flow types, not a new field
> (which are defined as RXH_*). If we want to hash on an extra field,
> I think we need to specify that field as well?

I've been really struggling with this...
When I read the Intel ICE documentation, it suggests that in RSS, TEID
can be an additional input.
However, I couldn't think of a reason not to include TEID when
enabling RSS for GTP cases.

https://www.intel.com/content/www/us/en/content-details/617015/intel-ethernet-controller-e810-dynamic-device-personalization-ddp-technology-guide.html
(cf. Table 8. Patterns and Input Sets for iavf RSS)

However, for Flow Director, it's clear that you'd want to include the
TEID field. But since I found that someone from Intel has already
configured it to use TEID with Flow Director, I thought maybe we don't
need to add the TEID parameter for now.

https://patchwork.ozlabs.org/project/intel-wired-lan/cover/20210126065206.137422-1-haiyue.wang@intel.com/

If we want to include something other than TEID (e.g., QFI) in Flow
Director, I think it would be better to prepare a new field.

2023年10月11日(水) 11:10 Jakub Kicinski <kuba@...nel.org>:
>
> On Wed, 11 Oct 2023 10:56:17 +0900 takeru hayasaka wrote:
> > GTP generates a flow that includes an ID called TEID to identify the
> > tunnel. This tunnel is created for each UE (User Equipment).
> > By performing RSS based on this flow, it is possible to apply RSS for
> > each communication unit from the UE.
> > Without this, RSS would only be effective within the range of IP addresses.
> > For instance, the PGW can only perform RSS within the IP range of the SGW.
> > What I'm trying to say is that RSS based solely on IP addresses can be
> > problematic from a load distribution perspective, especially if
> > there's a bias in the terminals connected to a particular base
> > station.
> > As a reference that discusses a similar topic, please see the link
> > below(is not RSS, is TEID Flow):
> > https://docs.nvidia.com/networking-ethernet-software/cumulus-linux-56/Layer-3/Routing/Equal-Cost-Multipath-Load-Sharing/#gtp-hashing
>
> Makes sense, thanks for the extra information. I think it would be
> worth adding all of this to the commit message!
>
> Regarding the patch - you are only adding flow types, not a new field
> (which are defined as RXH_*). If we want to hash on an extra field,
> I think we need to specify that field as well?
>
> > Thank you for your understanding.
> > ---
> > Sorry! My email was blocked because it wasn't sent in plain text mode.
> > I've made the necessary changes and will resend it.
>
> No worries! Additional request - in the future please prefer the
> bottom-posting or interleaved style of replies:
> https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

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