[dpdk-dev] [dpdk-stable] [PATCH] app/testpmd: fix queue Rx and Tx offload reconfig cmd

[Yu, DapengX]

> -----Original Message-----
> From: Li, Xiaoyun <xiaoyun.li at intel.com>
> Sent: Friday, April 9, 2021 3:50 PM
> To: Yu, DapengX <dapengx.yu at intel.com>; Yigit, Ferruh
> <ferruh.yigit at intel.com>; Zhang, Qi Z <qi.z.zhang at intel.com>
> Cc: dev at dpdk.org; stable at dpdk.org
> Subject: RE: [dpdk-stable] [PATCH] app/testpmd: fix queue Rx and Tx offload
> reconfig cmd
> 
> 
> 
> > -----Original Message-----
> > From: Yu, DapengX <dapengx.yu at intel.com>
> > Sent: Friday, April 9, 2021 13:25
> > To: Yigit, Ferruh <ferruh.yigit at intel.com>; Li, Xiaoyun
> > <xiaoyun.li at intel.com>; Zhang, Qi Z <qi.z.zhang at intel.com>
> > Cc: dev at dpdk.org; stable at dpdk.org
> > Subject: RE: [dpdk-stable] [PATCH] app/testpmd: fix queue Rx and Tx
> > offload reconfig cmd
> >
> >
> >
> > > -----Original Message-----
> > > From: Yigit, Ferruh <ferruh.yigit at intel.com>
> > > Sent: Thursday, April 8, 2021 11:42 PM
> > > To: Yu, DapengX <dapengx.yu at intel.com>; Li, Xiaoyun
> > > <xiaoyun.li at intel.com>; Zhang, Qi Z <qi.z.zhang at intel.com>
> > > Cc: dev at dpdk.org; stable at dpdk.org
> > > Subject: Re: [dpdk-stable] [PATCH] app/testpmd: fix queue Rx and Tx
> > > offload reconfig cmd
> > >
> > > On 4/1/2021 9:28 AM, dapengx.yu at intel.com wrote:
> > > > From: Dapeng Yu <dapengx.yu at intel.com>
> > > >
> > > > Configure per queue rx offloading and per queue tx offloading
> > > > command shouldn't trigger the rte_eth_dev_configure() to
> > > > reconfigure
> > device.
> > > >
> > > > The patch sets the queue reconfiguration flag only, and does not
> > > > set the device reconfiguration flag. Therefore after port is
> > > > restarted,
> > > > rte_eth_dev_configure() will not be called again.
> > > >
> > >
> > > Just to clarify the impact, was calling 'rte_eth_dev_configure()'
> > > causing any problem, is this fixing any issue?
> > > Or is this patch an optimization to eliminate an unnecessary call?
> > >
> > This patch does fix an issue, and it also eliminates an unnecessary call.
> >
> > The issue is:
> > per-queue configuration, for example: port 0 rxq 0 rx_offload
> > jumbo_frame off triggers the per-device configuration change: the RSS
> > key is reconfigured and changes after rte_eth_dev_configure() is
> > called on ICE PMD driver, that cause a test case failure.
> >
> 
> Hmmm. I agree on the following. It doesn't need dev_configure. That's why I
> give you ack.
> 
> But your issue. Shouldn't you fix the driver? The vsi->rss_key[] just updated
> itself as a random value when dev_conf doesn't contain one.
> But your case is dev_conf doesn't contain new rss key, but vsi->rss_key is not
> null. In this case, it should keep the same not get a new random key.
> 
In current implementation, dev->data->dev_conf.rx_adv_conf.rss_conf in PMD
does not hold the rss_key value if user does not set it in the input parameter of rte_eth_dev_configure(). 

Even if PMD generate one automatically, it will not be saved in dev->data->dev_conf.rx_adv_conf.rss_conf. 

When user want to get rss_key, it will be retrieved on the fly from hardware, but not from any variable
in PMD.

So PMD (ice and i40e) think only rss_key  which is set by user via rte_eth_dev_configure() can be reused
when port is reconfigured.

If it is not present, PMD will generate one by itself anyway even if it is present in vsi->rss_key.

I don’t think this behavior is wrong, so did not fix ice PMD.

> > There is an unnecessary call in original implementation because both
> > cmd_config_per_queue_rx_offload_parsed() and
> > cmd_config_per_queue_tx_offload_parsed()
> > does not update the "port->dev_conf" which hold the port
> > configuration, therefore there is no need to call rte_eth_dev_configure().