Re: [PATCH v2 4/4] net/i40e: enable deferred queue setup

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Zhang, Qi Z
> Sent: Thursday, March 15, 2018 3:22 AM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; thomas@monjalon.net
> Cc: dev@dpdk.org; Xing, Beilei <beilei.xing@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>
> Subject: RE: [dpdk-dev] [PATCH v2 4/4] net/i40e: enable deferred queue setup
> 
> 
> 
> > -----Original Message-----
> > From: Ananyev, Konstantin
> > Sent: Wednesday, March 14, 2018 8:36 PM
> > To: Zhang, Qi Z <qi.z.zhang@intel.com>; thomas@monjalon.net
> > Cc: dev@dpdk.org; Xing, Beilei <beilei.xing@intel.com>; Wu, Jingjing
> > <jingjing.wu@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Zhang, Qi Z
> > <qi.z.zhang@intel.com>
> > Subject: RE: [dpdk-dev] [PATCH v2 4/4] net/i40e: enable deferred queue
> > setup
> >
> >
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Qi Zhang
> > > Sent: Friday, March 2, 2018 4:13 AM
> > > To: thomas@monjalon.net
> > > Cc: dev@dpdk.org; Xing, Beilei <beilei.xing@intel.com>; Wu, Jingjing
> > > <jingjing.wu@intel.com>; Lu, Wenzhuo <wenzhuo.lu@intel.com>; Zhang,
> > Qi
> > > Z <qi.z.zhang@intel.com>
> > > Subject: [dpdk-dev] [PATCH v2 4/4] net/i40e: enable deferred queue
> > > setup
> > >
> > > Expose the deferred queue configuration capability and enhance
> > > i40e_dev_[rx|tx]_queue_[setup|release] to handle the situation when
> > > device already started.
> > >
> > > Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
> > > ---
> > >  drivers/net/i40e/i40e_ethdev.c |  6 ++++
> > >  drivers/net/i40e/i40e_rxtx.c   | 62
> > ++++++++++++++++++++++++++++++++++++++++--
> > >  2 files changed, 66 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/i40e/i40e_ethdev.c
> > > b/drivers/net/i40e/i40e_ethdev.c index 06b0f03a1..843a0c42a 100644
> > > --- a/drivers/net/i40e/i40e_ethdev.c
> > > +++ b/drivers/net/i40e/i40e_ethdev.c
> > > @@ -3195,6 +3195,12 @@ i40e_dev_info_get(struct rte_eth_dev *dev,
> > struct rte_eth_dev_info *dev_info)
> > >  		DEV_TX_OFFLOAD_GRE_TNL_TSO |
> > >  		DEV_TX_OFFLOAD_IPIP_TNL_TSO |
> > >  		DEV_TX_OFFLOAD_GENEVE_TNL_TSO;
> > > +	dev_info->deferred_queue_config_capa =
> > > +		DEV_DEFERRED_RX_QUEUE_SETUP |
> > > +		DEV_DEFERRED_TX_QUEUE_SETUP |
> > > +		DEV_DEFERRED_RX_QUEUE_RELEASE |
> > > +		DEV_DEFERRED_TX_QUEUE_RELEASE;
> > > +
> > >  	dev_info->hash_key_size = (I40E_PFQF_HKEY_MAX_INDEX + 1) *
> > >  						sizeof(uint32_t);
> > >  	dev_info->reta_size = pf->hash_lut_size; diff --git
> > > a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c index
> > > 1217e5a61..e5f532cf7 100644
> > > --- a/drivers/net/i40e/i40e_rxtx.c
> > > +++ b/drivers/net/i40e/i40e_rxtx.c
> > > @@ -1712,6 +1712,7 @@ i40e_dev_rx_queue_setup(struct rte_eth_dev
> > *dev,
> > >  	uint16_t len, i;
> > >  	uint16_t reg_idx, base, bsf, tc_mapping;
> > >  	int q_offset, use_def_burst_func = 1;
> > > +	int ret = 0;
> > >
> > >  	if (hw->mac.type == I40E_MAC_VF || hw->mac.type ==
> > I40E_MAC_X722_VF) {
> > >  		vf = I40EVF_DEV_PRIVATE_TO_VF(dev->data->dev_private);
> > > @@ -1841,6 +1842,25 @@ i40e_dev_rx_queue_setup(struct rte_eth_dev
> > *dev,
> > >  			rxq->dcb_tc = i;
> > >  	}
> > >
> > > +	if (dev->data->dev_started) {
> > > +		ret = i40e_rx_queue_init(rxq);
> > > +		if (ret != I40E_SUCCESS) {
> > > +			PMD_DRV_LOG(ERR,
> > > +				    "Failed to do RX queue initialization");
> > > +			return ret;
> > > +		}
> > > +		if (ad->rx_vec_allowed)
> >
> > Better to check what rx function is installed right now.
> Yes, it should be fixed, need to return fail if any conflict
> >
> > > +			i40e_rxq_vec_setup(rxq);
> > > +		if (!rxq->rx_deferred_start) {
> > > +			ret = i40e_dev_rx_queue_start(dev, queue_idx);
> >
> > I don't think it is a good idea to start/stop queue inside
> > queue_setup/queue_release.
> > There is special API (queue_start/queue_stop) to do this.
> 
> The idea is if dev already started, the queue is supposed to be started automatically after queue_setup.

Why is that?
Might be user doesn't want to start queue, might be he only wants to start it.
Might be he would need to call queue_setup() once again later before starting it - based on some logic?
If the user wants to setup and start the queue immediately he can always do:

rc = queue_setup(...);
if (rc == 0)
   queue_start(...);

We have a pretty well defined API here let's keep it like that.
Konstantin