Re: [dpdk-dev] [PATCH v15] app/testpmd: support multi-process

["Min Hu (Connor)" <humin29@huawei.com>]

Hi,Andrew ,

在 2021/7/8 20:30, Andrew Rybchenko 写道:
> On 7/8/21 3:20 PM, Min Hu (Connor) wrote:
>> Hi, Andrew ,
>>
>> 在 2021/7/2 20:47, Andrew Rybchenko 写道:
>>> On 7/2/21 3:09 PM, Andrew Rybchenko wrote:
>>>> From: "Min Hu (Connor)" <humin29@huawei.com>
>>>>
>>>> For example the following commands run two testpmd processes:
>>>>
>>>>    * the primary process:
>>>>
>>>> ./dpdk-testpmd --proc-type=auto -l 0-1 -- -i \
>>>>      --rxq=4 --txq=4 --num-procs=2 --proc-id=0
>>>>
>>>>    * the secondary process:
>>>>
>>>> ./dpdk-testpmd --proc-type=auto -l 2-3 -- -i \
>>>>      --rxq=4 --txq=4 --num-procs=2 --proc-id=1
>>>>
>>>> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
>>>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
>>>> Signed-off-by: Andrew Rybchenko <Andrew.Rybchenko@oktetlabs.ru>
>>>> Acked-by: Xiaoyun Li <xiaoyun.li@intel.com>
>>>> Acked-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
>>>> Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>
>>>
>>> [snip]
>>>
>>>> diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c
>>>> index 1cdd3cdd1..a5da0c272 100644
>>>> --- a/app/test-pmd/testpmd.c
>>>> +++ b/app/test-pmd/testpmd.c
>>>> @@ -520,6 +520,62 @@ enum rte_eth_rx_mq_mode rx_mq_mode =
>>>> ETH_MQ_RX_VMDQ_DCB_RSS;
>>>>     */
>>>>    uint32_t eth_link_speed;
>>>>    +/*
>>>> + * ID of the current process in multi-process, used to
>>>> + * configure the queues to be polled.
>>>> + */
>>>> +int proc_id;
>>>> +
>>>> +/*
>>>> + * Number of processes in multi-process, used to
>>>> + * configure the queues to be polled.
>>>> + */
>>>> +unsigned int num_procs = 1;
>>>> +
>>>> +static int
>>>> +eth_dev_configure_mp(uint16_t port_id, uint16_t nb_rx_q, uint16_t
>>>> nb_tx_q,
>>>> +              const struct rte_eth_conf *dev_conf)
>>>> +{
>>>> +    if (is_proc_primary())
>>>> +        return rte_eth_dev_configure(port_id, nb_rx_q, nb_tx_q,
>>>> +                    dev_conf);
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int
>>>> +eth_dev_start_mp(uint16_t port_id)
>>>> +{
>>>> +    if (is_proc_primary())
>>>> +        return rte_eth_dev_start(port_id);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static int
>>>> +eth_dev_stop_mp(uint16_t port_id)
>>>> +{
>>>> +    if (is_proc_primary())
>>>> +        return rte_eth_dev_stop(port_id);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static void
>>>> +mempool_free_mp(struct rte_mempool *mp)
>>>> +{
>>>> +    if (is_proc_primary())
>>>> +        rte_mempool_free(mp);
>>>> +}
>>>> +
>>>> +static int
>>>> +eth_dev_set_mtu_mp(uint16_t port_id, uint16_t mtu)
>>>> +{
>>>> +    if (is_proc_primary())
>>>> +        return rte_eth_dev_set_mtu(port_id, mtu);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>
>>> I think above functions should be removed and corresponding
>>> checks should be done in caller directly since above functions
>>> are used in single place only and just hide what actually
>>> happens in the case of secondary process. It is very
>>> misleading.
>>>
>> This was done as Ferruh suggested in V9， and this could reduce
>> the complexity for testpmd when added by the multi-process support.
>>> [snip]
>>>
>>>> @@ -2495,21 +2565,24 @@ start_port(portid_t pid)
>>>>                    return -1;
>>>>                }
>>>>                /* configure port */
>>>> -            diag = rte_eth_dev_configure(pi, nb_rxq + nb_hairpinq,
>>>> -                             nb_txq + nb_hairpinq,
>>>> -                             &(port->dev_conf));
>>>> +            diag = eth_dev_configure_mp(pi,
>>>> +                         nb_rxq + nb_hairpinq,
>>>> +                         nb_txq + nb_hairpinq,
>>>> +                         &(port->dev_conf));
>>>>                if (diag != 0) {
>>>> -                if (rte_atomic16_cmpset(&(port->port_status),
>>>> -                RTE_PORT_HANDLING, RTE_PORT_STOPPED) == 0)
>>>> -                    printf("Port %d can not be set back "
>>>> -                            "to stopped\n", pi);
>>>> +                if (rte_atomic16_cmpset(
>>>> +                        &(port->port_status),
>>>> +                        RTE_PORT_HANDLING,
>>>> +                        RTE_PORT_STOPPED) == 0)
>>>> +                    printf("Port %d cannot be set back to stopped\n",
>>>> +                        pi);
>>>
>>> Unrelated changes in the patch should be avoided since
>>> it just makes the review harder.This will be fixed in v16.
>>>
>>>>                    printf("Fail to configure port %d\n", pi);
>>>>                    /* try to reconfigure port next time */
>>>>                    port->need_reconfig = 1;
>>>>                    return -1;
>>>>                }
>>>>            }
>>>> -        if (port->need_reconfig_queues > 0) {
>>>> +        if (port->need_reconfig_queues > 0 && is_proc_primary()) {
>>>>                port->need_reconfig_queues = 0;
>>>>                /* setup tx queues */
>>>>                for (qi = 0; qi < nb_txq; qi++) {
>>>> @@ -2532,8 +2605,8 @@ start_port(portid_t pid)
>>>>                    if (rte_atomic16_cmpset(&(port->port_status),
>>>>                                RTE_PORT_HANDLING,
>>>>                                RTE_PORT_STOPPED) == 0)
>>>> -                    printf("Port %d can not be set back "
>>>> -                            "to stopped\n", pi);
>>>> +                    printf("Port %d cannot be set back to stopped\n",
>>>> +                        pi);
>>>
>>> Unrelated changes in the patch should be avoided.
>> This will be fixed in v16.
>>>
>>>>                    printf("Fail to configure port %d tx queues\n",
>>>>                           pi);
>>>>                    /* try to reconfigure queues next time */
>>>> @@ -2610,16 +2683,16 @@ start_port(portid_t pid)
>>>>            cnt_pi++;
>>>>              /* start port */
>>>> -        diag = rte_eth_dev_start(pi);
>>>> +        diag = eth_dev_start_mp(pi);
>>>>            if (diag < 0) {
>>>>                printf("Fail to start port %d: %s\n", pi,
>>>>                       rte_strerror(-diag));
>>>>                  /* Fail to setup rx queue, return */
>>>>                if (rte_atomic16_cmpset(&(port->port_status),
>>>> -                RTE_PORT_HANDLING, RTE_PORT_STOPPED) == 0)
>>>> -                printf("Port %d can not be set back to "
>>>> -                            "stopped\n", pi);
>>>> +            RTE_PORT_HANDLING, RTE_PORT_STOPPED) == 0)
>>>> +                printf("Port %d cannot be set back to stopped\n",
>>>> +                       pi);
>>>
>>> Unrelated changes in the patch should be avoided.
>> This will be fixed in v16.
>>>
>>> [snip]
>>>
>>>> diff --git a/doc/guides/testpmd_app_ug/run_app.rst
>>>> b/doc/guides/testpmd_app_ug/run_app.rst
>>>> index eb4831835..348e5fcac 100644
>>>> --- a/doc/guides/testpmd_app_ug/run_app.rst
>>>> +++ b/doc/guides/testpmd_app_ug/run_app.rst
>>>> @@ -545,3 +545,85 @@ The command line options are:
>>>>        bit 0 - two hairpin ports loop
>>>>          The default value is 0. Hairpin will use single port mode and
>>>> implicit Tx flow mode.
>>>> +
>>>> +
>>>> +Testpmd Multi-Process Command-line Options
>>>> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>> +
>>>> +The following are the command-line options for testpmd multi-process
>>>> support:
>>>> +
>>>> +*   primary process:
>>>> +
>>>> +.. code-block:: console
>>>> +
>>>> +       sudo ./dpdk-testpmd --proc-type=auto -l 0-1 -- -i --rxq=4
>>>> --txq=4 \
>>>> +            --num-procs=2 --proc-id=0
>>>> +
>>>> +*   secondary process:
>>>> +
>>>> +.. code-block:: console
>>>> +
>>>> +       sudo ./dpdk-testpmd --proc-type=auto -l 2-3 -- -i --rxq=4
>>>> --txq=4 \
>>>> +            --num-procs=2 --proc-id=1
>>>> +
>>>> +The command line options are:
>>>> +
>>>> +*   ``--num-procs=N``
>>>> +
>>>> +    The number of processes which will be used.
>>>> +
>>>> +*   ``--proc-id=ID``
>>>> +
>>>> +    The ID of the current process (ID < num-procs). ID should be
>>>> different in
>>>> +    primary process and secondary process, which starts from '0'.
>>>> +
>>>> +Calculation rule for queue:
>>>> +All queues are allocated to different processes based on
>>>> ``proc_num`` and
>>>> +``proc_id``.
>>>> +Calculation rule for the testpmd to allocate queues to each process:
>>>> +
>>>> +* start(queue start id) = proc_id * nb_q / num_procs
>>>> +
>>>> +* end(queue end id) = start + nb_q / num_procs
>>>> +
>>>> +For example, if testpmd is configured to have 4 Tx and Rx queues,
>>>> +queues 0 and 1 will be used by the primary process and
>>>> +queues 2 and 3 will be used by the secondary process.
>>>> +
>>>> +The number of queues should be a multiple of the number of
>>>> processes. If not,
>>>> +redundant queues will exist after queues are allocated to processes.
>>>> If RSS
>>>> +is enabled, packet loss occurs when traffic is sent to all processes
>>>> at the same
>>>> +time. Some traffic goes to redundant queues and cannot be forwarded.
>>>> +
>>>> +All the dev ops is supported in primary process. While secondary
>>>> process is
>>>> +not permitted to allocate or release shared memory, so some ops are
>>>> not supported
>>>> +as follows:
>>>> +
>>>> +- ``dev_configure``
>>>> +- ``dev_start``
>>>> +- ``dev_stop``
>>>> +- ``rx_queue_setup``
>>>> +- ``tx_queue_setup``
>>>> +- ``rx_queue_release``
>>>> +- ``tx_queue_release``
>>>> +
>>>> +So, any command from testpmd which calls those APIs will not be
>>>> supported in
>>>> +secondary process, like:
>>>> +
>>>> +.. code-block:: console
>>>> +
>>>> +    port config all rxq|txq|rxd|txd <value>
>>>> +    port config <port_id> rx_offload xxx on/off
>>>> +    port config <port_id> tx_offload xxx on/off
>>>> +
>>>> +etc.
>>>
>>> I did the formatting cleanup, but I still think that testpmd
>>> guide should not dive into such level of details. It should
>>> rather highlight multi-process behaviour specifics.
>>>
>>> Shouldn't testpmd store state in shared memory to avoid
>>> problems when primary is stopped while secondary is running
>> This could be taken into consideration in future.
>>
>>>
>>> Some testpmd features rely on reconfigure (i.e. simply change
>>> configuration and set flag that reconfigure is required), but
>>> configure does nothing and will simply ignore new settings.
>>> So, it could look very-very confusing from user point of view.
>>>
>>> I'm not sure that it is acceptable to apply the patch in such
>>> state and open huge number of bugs in testpmd behaviour when
>>> multi-process is used.
>>>
>>> I'd even consider to exclude unsupported commands from help
>>> etc. However, such level of care about user could be excessive
>>> for test tool.
>> This has been done in doc.
>>>
>>> IMHO, it should be no requirement to repeat the primary
>>> process command-line configuration in the second process
>>> command line (see --rxq=4 --txq=4 above). The information
>>> should be obtained from shared state. In theory primary
>>> process could even change some settings in interactive
>> We think keeping the command line in consistent between primary
>> and secondary is easy to understand for users. While shared memory for
>> keeping in order or communicating could be performed,but this could
>> be done in future patch.
>>
>>> mode. I think testpmd should guarantee consistent behaviour
>>> even in such conditions. I.e. do not allow to stop ports
>>> used by forwarding running in secondary processes.
>>> Run-time queues setup and deferred start should be very
>>> carefully handled as well.
>>   ``dev_stop`` is not allowed in secondary, which has described in doc.
> 
> I'm talking about dev_stop in primary while secondary is
> running.
> 
>>>> +
>>>> +Stats is supported, stats will not change when one quits and starts,
>>>> as they
>>>> +share the same buffer to store the stats. Flow rules are maintained
>>>> in process
>>>> +level: primary and secondary has its own flow list (but one flow
>>>> list in HW).
>>>> +The two can see all the queues, so setting the flow rules for the
>>>> other is OK.
>>>> +But in the testpmd primary process receiving or transmitting packets
>>>> from the
>>>> +queue allocated for secondary process is not permitted, and same for
>>>> secondary
>>>> +process.
>>>> +
>>>> +Flow API and RSS are supported.
>>>> Thanks for your comment,
>> This patch supports basic function for multi-process support in testpmd.
>> I think other patches in future could enhance or optimize it, thanks.
> 
> IMHO, as I state above, current state is insufficient to
> consider is a start point to be applied.
OK, what is the critical(the most important) as a start point to be applied?
I will take action to fix it,as I will the patch could be applied before 
V21.08.

> .
>