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Date:      Tue, 24 Mar 2015 08:49:31 -0700
From:      hiren panchasara <hiren@strugglingcoder.info>
To:        Jack Vogel <jfvogel@gmail.com>
Cc:        Jack F Vogel <jfv@freebsd.org>, FreeBSD Net <freebsd-net@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, erj@freebsd.org, Jason Wolfe <nitroboost@gmail.com>
Subject:   Re: Full 32bit flowid from igb(4)
Message-ID:  <20150324154931.GC53237@strugglingcoder.info>
In-Reply-To: <CAFOYbc=f3OT85z50uqYEnBUkEej=8FRnRP8TpQuTStgqUEoDTA@mail.gmail.com>
References:  <20150323233908.GT53237@strugglingcoder.info> <20150323234214.GU53237@strugglingcoder.info> <CAFOYbc=f3OT85z50uqYEnBUkEej=8FRnRP8TpQuTStgqUEoDTA@mail.gmail.com>

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On 03/23/15 at 04:58P, Jack Vogel wrote:
> I think that line was there at one time outside the RSS define,

I believe this was added by Adrian as part of RSS work and was not there
before. I may be wrong.
> I'd have to
> take a look at
> the code a bit more, or maybe Eric will....

I'll wait for the comments.

Cheers,
Hiren
>=20
> Jack
>=20
>=20
> On Mon, Mar 23, 2015 at 4:42 PM, hiren panchasara <
> hiren@strugglingcoder.info> wrote:
>=20
> > Correcting Eric's email and subject line.
> >
> > On 03/23/15 at 04:39P, hiren panchasara wrote:
> > > scottl@freebsd.org
> > > Bcc:
> > > Subject: Full 32bit flowid from igb(4) [was: Re: Unbalanced LACP link]
> > > Reply-To:
> > > In-Reply-To: <20150319175145.GH53237@strugglingcoder.info>
> > >
> > > On 03/19/15 at 10:51P, hiren panchasara wrote:
> > > > On 03/17/15 at 12:34P, Adrian Chadd wrote:
> > > > > On 17 March 2015 at 11:33, Jason Wolfe <nitroboost@gmail.com> wro=
te:
> > > > > > On Mon, Mar 16, 2015 at 2:43 AM, Hans Petter Selasky <
> > hps@selasky.org> wrote:
> > > > > >> On 03/16/15 10:37, Vitalii Duk wrote:
> > > > > >>>
> > > > > >>> I've changed use_flowid to 0 and it helped! But isn't it sett=
ing
> > > > > >>> significant? In a description it says "Shift flowid bits to
> > prevent
> > > > > >>> multiqueue collisions".
> > > > > >>
> > > > > >>
> > > > > >> Hi,
> > > > > >>
> > > > > >> Maybe your ethernet hardware is not properly setting the m_flo=
wid
> > ...
> > > > > >>
> > > > > >> --HPS
> > > > > >>
> > > > > >
> > > > > > Flip use_flowid back to 1 and try setting
> > > > > > net.link.lagg.default_flowid_shift / net.link.lagg.X.flowid_shi=
ft
> > to 0
> > > > > > as Hiren suggested.  r260179 added this shift, which has caused=
 us
> > > > > > balancing issues with the i350/igb.
> > > > > >
> > > > > > https://svnweb.freebsd.org/base?view=3Drevision&revision=3D2601=
79
> > > > > >
> > > > > > Based on Adrian's comment about igb/ixgbe not setting the 'full
> > > > > > flowid' under normal conditions, does that mean this shift shou=
ld
> > be 0
> > > > > > by default to ensure we don't break balancing for devices that =
only
> > > > > > set the CPU/MSIX queue?
> > > > >
> > > > > Or we can just see if there's anything wrong with putting the ful=
l 32
> > > > > bit RSS flowid in received packets that have them.
> > > >
> > > > It'd be nice to have but for now I am proposing following to fix a
> > known
> > > > broken case because of an optimization:
> > > > https://reviews.freebsd.org/D2098
> > >
> > > Turns out, setting flowid_shift to 0 is not the correct solution. Ple=
ase
> > > look at the review above for more details.
> > >
> > > Looking at the code, we have a way to get full flowid but it's hidden
> > > under "ifdef RSS":
> > >     rxr->fmp->m_pkthdr.flowid =3D le32toh(cur->wb.lower.hi_dword.rss);
> > >
> > > Using just this line gives me good hash on I350 igb(4) chipset that we
> > > have.
> > >
> > > Is it possible to expose this outside RSS? Would this break other
> > > things/chips?
> > >
> > > Cheers,
> > > Hiren
> >
> >
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