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Message-ID: <309B89C4C689E141A5FF6A0C5FB2118B8C83B016@ORSMSX101.amr.corp.intel.com>
Date: Tue, 17 Apr 2018 00:55:21 +0000
From: "Brown, Aaron F" <aaron.f.brown@...el.com>
To: "Gomes, Vinicius" <vinicius.gomes@...el.com>,
"intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>
CC: "Gomes, Vinicius" <vinicius.gomes@...el.com>,
"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"Sanchez-Palencia, Jesus" <jesus.sanchez-palencia@...el.com>,
"Guedes, Andre" <andre.guedes@...el.com>
Subject: RE: [next-queue PATCH] igb: Fix the transmission mode of queue 0
for Qav mode
> From: Brown, Aaron F
> Sent: Friday, April 13, 2018 7:28 PM
> To: 'Vinicius Costa Gomes' <vinicius.gomes@...el.com>; intel-wired-
> lan@...ts.osuosl.org
> Cc: Gomes, Vinicius <vinicius.gomes@...el.com>; Kirsher, Jeffrey T
> <jeffrey.t.kirsher@...el.com>; netdev@...r.kernel.org; Sanchez-Palencia,
> Jesus <jesus.sanchez-palencia@...el.com>; Guedes, Andre
> <andre.guedes@...el.com>
> Subject: RE: [next-queue PATCH] igb: Fix the transmission mode of queue 0
> for Qav mode
>
> > From: netdev-owner@...r.kernel.org [mailto:netdev-
> > owner@...r.kernel.org] On Behalf Of Vinicius Costa Gomes
> > Sent: Friday, March 30, 2018 5:07 PM
> > To: intel-wired-lan@...ts.osuosl.org
> > Cc: Gomes, Vinicius <vinicius.gomes@...el.com>; Kirsher, Jeffrey T
> > <jeffrey.t.kirsher@...el.com>; netdev@...r.kernel.org; Sanchez-Palencia,
> > Jesus <jesus.sanchez-palencia@...el.com>; Guedes, Andre
> > <andre.guedes@...el.com>
> > Subject: [next-queue PATCH] igb: Fix the transmission mode of queue 0 for
> > Qav mode
> >
> > When Qav mode is enabled, queue 0 should be kept on Stream
> Reservation
> > mode. From the i210 datasheet, section 8.12.19:
> >
> > "Note: Queue0 QueueMode must be set to 1b when TransmitMode is set
> to
> > Qav." ("QueueMode 1b" represents the Stream Reservation mode)
> >
> > The solution is to give queue 0 the all the credits it might need, so
> > it has priority over queue 1.
> >
> > A situation where this can happen is when cbs is "installed" only on
> > queue 1, leaving queue 0 alone. For example:
> >
> > $ tc qdisc replace dev enp2s0 handle 100: parent root mqprio num_tc 3 \
> > map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 queues 1@0 1@1 2@2 hw 0
> >
> > $ tc qdisc replace dev enp2s0 parent 100:2 cbs locredit -1470 \
> > hicredit 30 sendslope -980000 idleslope 20000 offload 1
> >
> > Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@...el.com>
> > ---
> > drivers/net/ethernet/intel/igb/igb_main.c | 17 ++++++++++++++++-
> > 1 file changed, 16 insertions(+), 1 deletion(-)
> >
>
> Tested by: Aaron Brown <aaron.f.brown@...el.com>
Tested-by: Aaron Brown <aaron.f.brown@...el.com>
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