On 4/24/2018 10:29 PM, Jeff Kirsher wrote:

From: Vinicius Costa Gomes <vinicius.go...@intel.com>

When Qav mode is enabled, queue 0 should be kept on Stream Reservation

   s/on/in/?

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.go...@intel.com>
Tested-by: Aaron Brown <aaron.f.br...@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirs...@intel.com>
[...]

MBR, Sergei

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