RE: [next-queue PATCH] igb: Fix the transmission mode of queue 0 for Qav mode

[Brown, Aaron F]

> From: Brown, Aaron F
> Sent: Friday, April 13, 2018 7:28 PM
> To: 'Vinicius Costa Gomes' <vinicius.go...@intel.com>; intel-wired-
> l...@lists.osuosl.org
> Cc: Gomes, Vinicius <vinicius.go...@intel.com>; Kirsher, Jeffrey T
> <jeffrey.t.kirs...@intel.com>; netdev@vger.kernel.org; Sanchez-Palencia,
> Jesus <jesus.sanchez-palen...@intel.com>; Guedes, Andre
> <andre.gue...@intel.com>
> Subject: RE: [next-queue PATCH] igb: Fix the transmission mode of queue 0
> for Qav mode
> 
> > From: netdev-ow...@vger.kernel.org [mailto:netdev-
> > ow...@vger.kernel.org] On Behalf Of Vinicius Costa Gomes
> > Sent: Friday, March 30, 2018 5:07 PM
> > To: intel-wired-...@lists.osuosl.org
> > Cc: Gomes, Vinicius <vinicius.go...@intel.com>; Kirsher, Jeffrey T
> > <jeffrey.t.kirs...@intel.com>; netdev@vger.kernel.org; Sanchez-Palencia,
> > Jesus <jesus.sanchez-palen...@intel.com>; Guedes, Andre
> > <andre.gue...@intel.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 -98 idleslope 2 offload 1
> >
> > Signed-off-by: Vinicius Costa Gomes <vinicius.go...@intel.com>
> > ---
> >  drivers/net/ethernet/intel/igb/igb_main.c | 17 -
> >  1 file changed, 16 insertions(+), 1 deletion(-)
> >
> 
> Tested by: Aaron Brown <aaron.f.br...@intel.com>
Tested-by: Aaron Brown <aaron.f.br...@intel.com>

RE: [next-queue PATCH] igb: Fix the transmission mode of queue 0 for Qav mode

[Brown, Aaron F]

> From: netdev-ow...@vger.kernel.org [mailto:netdev-
> ow...@vger.kernel.org] On Behalf Of Vinicius Costa Gomes
> Sent: Friday, March 30, 2018 5:07 PM
> To: intel-wired-...@lists.osuosl.org
> Cc: Gomes, Vinicius ; Kirsher, Jeffrey T
> ; netdev@vger.kernel.org; Sanchez-Palencia,
> Jesus ; Guedes, Andre
> 
> 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 -98 idleslope 2 offload 1
> 
> Signed-off-by: Vinicius Costa Gomes 
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 17 -
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 

Tested by: Aaron Brown