[dpdk-dev] [PATCH 1/2] app/testpmd: update Rx RSS HASH offload when setting MQ RSS

[Wei Hu (Xavier)]

Hi, Ferruh Yigit

On 2020/9/23 0:21, Ferruh Yigit wrote:
> On 9/8/2020 3:16 AM, Wei Hu (Xavier) wrote:
>> From: Huisong Li <lihuisong at huawei.com>
>>
>> Currently, when starting testpmd application without '--disable-rss' and
>> the number of Rx queue configured is greater than 1, ETH_MQ_RX_RSS flag
>> is set in port->dev_conf.rxmode.mq_mode in testpmd application, and
>> DEV_RX_OFFLOAD_RSS_HASH flag is set in rx_offloads
>> (dev->data->dev_conf.rxmode.offloads) according to the ETH_MQ_RX_RSS
>> flag of rxmode.mq_mode in PMD drivers.
>>
>> However, DEV_RX_OFFLOAD_RSS_HASH is not set to rx_offloads maintained
>> in testpmd application, this will cause the inconsistent problem that
>> rx_offloads is different for testpmd and PMD drivers.
> 
> Yes for DEV_RX_OFFLOAD_RSS_HASH, application rx_offload config and PMD 
> one diverges, for *some* PMDs.
> 
> This is done to have the backward compatibility of the PMD behavior.
> 
> The PMDs that would like to write the provide the calculated hash value 
> back, overwrites the offload config to enable 'DEV_RX_OFFLOAD_RSS_HASH'. 
> And does more work than user requested, this shouldn't have any side 
> affect.
> Some doesn't provide the hash unless user explicitly requests it.
> 
> Applications shouldn't set it blindly, at least first check if PMD 
> supports it but even that case, unless it is needed I think HASH offload 
> shouldn't be requested by default.

OK, we are going to do modification to add check if PMD support 
DEV_RX_OFFLOAD_RSS_HASH before setting it as below:

  @@ -3356,11 +3356,13 @@ init_port_config(void)
            }
            if (port->dcb_flag == 0) {
               if (port->dev_conf.rx_adv_conf.rss_conf.rss_hf != 0) {
                    port->dev_conf.rxmode.mq_mode =
                        (enum rte_eth_rx_mq_mode)
                            (rx_mq_mode & ETH_MQ_RX_RSS);
  		  if (port->dev_info.rx_offload_capa &
		      DEV_RX_OFFLOAD_RSS_HASH)
  			port->dev_conf.rxmode.offloads |=
						DEV_RX_OFFLOAD_RSS_HASH;
              } else
                    port->dev_conf.rxmode.mq_mode = ETH_MQ_RX_NONE;
            }

Thanks, Xavier
> 
>>
>> Signed-off-by: Huisong Li <lihuisong at huawei.com>
>> Signed-off-by: Wei Hu (Xavier) <xavier.huwei at huawei.com>
>> ---
>>   app/test-pmd/testpmd.c | 6 ++++--
>>   1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
>> index 7842c3b..73543bb 100644
>> --- a/app/test-pmd/testpmd.c
>> +++ b/app/test-pmd/testpmd.c
>> @@ -3356,11 +3356,13 @@ init_port_config(void)
>>           }
>>           if (port->dcb_flag == 0) {
>> -            if( port->dev_conf.rx_adv_conf.rss_conf.rss_hf != 0)
>> +            if (port->dev_conf.rx_adv_conf.rss_conf.rss_hf != 0) {
>>                   port->dev_conf.rxmode.mq_mode =
>>                       (enum rte_eth_rx_mq_mode)
>>                           (rx_mq_mode & ETH_MQ_RX_RSS);
>> -            else
>> +                port->dev_conf.rxmode.offloads |=
>> +                            DEV_RX_OFFLOAD_RSS_HASH;
>> +            } else
>>                   port->dev_conf.rxmode.mq_mode = ETH_MQ_RX_NONE;
>>           }
>>