Re: [PATCH v3] app/test-pmd: fix not polling all queues without deferred starting

[Jie Hai <haijie1@huawei.com>]

On 2023/6/8 2:12, Ferruh Yigit wrote:
> On 5/29/2023 3:26 AM, Jie Hai wrote:
> 
>>
>> Each stream has a read-only "disabled" field that control if this
>> stream should be used to forward. This field depends on states
>> of Rx/Tx queues, please see
>> commit 3c4426db54fc ("app/testpmd: do not poll stopped queues").
>>
>> Currently, the testpmd and DPDK frameworks maintain queue state
>> separately. That of the primary process of testpmd are set by
>> deferred_start in the queue configuration. And that of the
>> framework(dev->data->rx_queue_state or dev->data->tx_queue_state)
>> is set when the driver enables/disables the queue, and it is
>> shared between the primary/secondary process.
>>
>> If the deferred_start is set, the queue is disabled and the
>> corresponding queue state in the framework changes to stopped.
>> However, the queue state in the framework does not only come from
>> this. If the primary/secondary process stops a queue, the related
>> queue state will change, too. However, the primary process of
>> testpmd does not know the change brought by this operation.
>> Therefore, setting the queue state in the primary testpmd by only
>> the deferred_start is unsafe.
>>
>> For example, Rx/Tx queues who are stopped before the operations of
>> stopping and starting port cannot forward packets after these
>> operations on primary process.
>>
>> Therefore, the primary process should getting the queue state from
>> of the framework as the secondary process does, please see commit
>> e065c9aa3e05 ("app/testpmd: fix secondary process packet forwarding").
>>
>> Fixes: 3c4426db54fc ("app/testpmd: do not poll stopped queues")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Jie Hai <haijie1@huawei.com>
>> ---
>> v1->v2:
>> 1. Fix misspelled word 'deferred'.
>> 2. Fix incorrect format of reference to commits.
>>
>> v2->v3
>> 1. Fix incorrect format of reference to commits.
>> ---
>>   app/test-pmd/testpmd.c | 19 +++----------------
>>   1 file changed, 3 insertions(+), 16 deletions(-)
>>
>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
>> index 5cb6f9252395..a07a67a2639e 100644
>> --- a/app/test-pmd/testpmd.c
>> +++ b/app/test-pmd/testpmd.c
>> @@ -2502,8 +2502,7 @@ start_packet_forwarding(int with_tx_first)
>>                  return;
>>
>>          if (stream_init != NULL) {
>> -               if (rte_eal_process_type() == RTE_PROC_SECONDARY)
>> -                       update_queue_state();
>> +               update_queue_state();
>>                  for (i = 0; i < cur_fwd_config.nb_fwd_streams; i++)
>>                          stream_init(fwd_streams[i]);
>>          }
>> @@ -2860,9 +2859,6 @@ rx_queue_setup(uint16_t port_id, uint16_t rx_queue_id,
>>                                      socket_id, rx_conf, mp);
>>          }
>>
>> -       ports[port_id].rxq[rx_queue_id].state = rx_conf->rx_deferred_start ?
>> -                                               RTE_ETH_QUEUE_STATE_STOPPED :
>> -                                               RTE_ETH_QUEUE_STATE_STARTED;
>>          return ret;
>>   }
>>
>> @@ -3129,9 +3125,6 @@ start_port(portid_t pid)
>>                          port->need_reconfig_queues = 0;
>>                          /* setup tx queues */
>>                          for (qi = 0; qi < nb_txq; qi++) {
>> -                               struct rte_eth_txconf *conf =
>> -                                                       &port->txq[qi].conf;
>> -
>>                                  if ((numa_support) &&
>>                                          (txring_numa[pi] != NUMA_NO_CONFIG))
>>                                          diag = rte_eth_tx_queue_setup(pi, qi,
>> @@ -3144,13 +3137,8 @@ start_port(portid_t pid)
>>                                                  port->socket_id,
>>                                                  &(port->txq[qi].conf));
>>
>> -                               if (diag == 0) {
>> -                                       port->txq[qi].state =
>> -                                               conf->tx_deferred_start ?
>> -                                               RTE_ETH_QUEUE_STATE_STOPPED :
>> -                                               RTE_ETH_QUEUE_STATE_STARTED;
>> +                               if (diag == 0)
>>                                          continue;
>> -                               }
>>
>>                                  /* Fail to setup tx queue, return */
>>                                  if (port->port_status == RTE_PORT_HANDLING)
>> @@ -3266,8 +3254,7 @@ start_port(portid_t pid)
>>                  pl[cfg_pi++] = pi;
>>          }
>>
>> -       if (rte_eal_process_type() == RTE_PROC_SECONDARY)
>> -               update_queue_state();
>> +       update_queue_state();
>>
> 
> As you described, issue seems caused by commit [1] using testpmd local
> queue state information to decide to forward or not on a stream.
> 
> There are other commands that update ethdev queue state, this is causing
> testpmd and ethdev state information to diverge and causes unexpected
> side effects.
> 
> 
> For the sample you provided, just above change (that updates queue state
> before port start) should be sufficient,
> also I guess it is OK to update state in 'start_packet_forwarding()' to
> be on safe side.
> 
> But not sure about to update deferred_start related changes in this
> patch, also details about it makes commit log complex to understand,
> what do you think to split deferred_start related changes to another patch?
> 
I think I should drop the changes on deferred_start. It may cause PMDs 
supporting 'deferred_start' but not supporting 
'rte_eth_tx_queue_info_get' or 'rte_eth_rx_queue_info_get' takes no 
effect when set 'deferred_start' on.

A better way is to check when updating the queue state. If this is the 
case, keep the testpmd state to the original value so that the original 
behavior is not changed.

> 
> In commit log, can you please refer to the patch that fixes similar
> issue for secondary process [2], that is relevant with this fix,
> reference may help to understand this issue better.
Ok. I will.
> 
> @Shiyang, can you please test secondary process fix this patch, to be
> sure this is not breaking it again?
> 
> 
> 
> [1]
> Fixes: 3c4426db54fc ("app/testpmd: do not poll stopped queues")
> 
> [2]
> 5028f207a4fa ("app/testpmd: fix secondary process packet forwarding")
> 
> .