[dpdk-dev] [PATCH v3 04/10] app/testpmd: convert to new Ethdev Tx offloads API

[Ananyev, Konstantin]

> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Lu, Wenzhuo
> Sent: Tuesday, January 9, 2018 11:37 AM
> To: Shahaf Shuler <shahafs at mellanox.com>; Wu, Jingjing <jingjing.wu at intel.com>; Yigit, Ferruh <ferruh.yigit at intel.com>
> Cc: dev at dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v3 04/10] app/testpmd: convert to new Ethdev Tx offloads API
> 
> Hi Shahaf,
> 
> > -----Original Message-----
> > From: Shahaf Shuler [mailto:shahafs at mellanox.com]
> > Sent: Tuesday, January 9, 2018 6:02 PM
> > To: Lu, Wenzhuo <wenzhuo.lu at intel.com>; Wu, Jingjing
> > <jingjing.wu at intel.com>; Yigit, Ferruh <ferruh.yigit at intel.com>
> > Cc: dev at dpdk.org
> > Subject: RE: [dpdk-dev] [PATCH v3 04/10] app/testpmd: convert to new
> > Ethdev Tx offloads API
> >
> > Tuesday, January 9, 2018 9:14 AM, Lu, Wenzhuo:
> > > > The original code doesn't have such restriction because testpmd
> > > > wasn't configuring Tx offloads at all. It used it's own Tx offloads
> > > > enum (which I removed on later patches) to indicate which offloads is set.
> > > > From the device perspective all the Tx offloads should be set.
> > > > It did had a way to configure offloads with txqflags parameter, but
> > > > this required queues reconfigurations.
> > > ' cmd_tx_vlan_set_parsed' is the function which configures TX vlan
> > insertion.
> > > This patch adds the restriction in it.
> > > For example, on ixgbe it does support on the fly configuration. APP
> > > doesn't need to stop the device or reconfigure the queues.
> >
> > What is mean is that in the old offloads API, all the Tx offloads were enabled
> > by default, besides the ones which were masked with txqflags.
> > This is why testpmd didn't have any limitation on changing the Tx offloads.
> > All of them were enabled, it just needed to choose with which one to use.
> >
> > Now, with the new offloads API, the Tx offloads are disabled by default, and
> > enabled per application need on device and queue configuration.
> > In order to call device/queue configuration the port must be stopped. This is
> > requirement from ethdev API.
> >
> > Now, there is an API in ethdev to configure Rx VLAN offloads on the flight for
> > supported devices.
> > If there are devices which supports it also in the Tx side, and you see a good
> > use case for that, then need to think of new API in ethdev to configure Tx
> > VLAN offloads on the flight.
> >
> > However, the plain conversion of testpmd from the old to the new API
> > requires the port to be stopped for all of the Tx offloads.
> Let's just talk about TX vlan insertion. Actually there's no ethdev API for it. And no configuration for it. Because vlan insertion is simple, it
> only need to add a vlan tag when transmitting packets.

You still need an appropriate TX function be selected, otherwise mbuf->vlan_tci will be just ignored.
So you still has to specify at queue_setup flag that you would like to have VLAN insertion offload enabled. 
Konstantin

> You can see it's per packet thing. APP can set the ol_flags and vlan_tci in the mbuf of every packet to enable this function for the packet or
> not. I think it does be a on the fly function on any NIC.