Re: [dpdk-dev] [PATCH v2 3/4] common_base: extend RTE_MAX_ETHPORTS from 32 to 1024

[Hemant Agrawal <hemant.agrawal@nxp.com>]

On 9/4/2017 3:57 PM, Ananyev, Konstantin wrote:
> Hi Zhiong,
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Yang, Zhiyong
>> Sent: Monday, September 4, 2017 11:05 AM
>> To: Richardson, Bruce <bruce.richardson@intel.com>
>> Cc: Yao, Lei A <lei.a.yao@intel.com>; dev@dpdk.org; thomas@monjalon.net; Yigit, Ferruh <ferruh.yigit@intel.com>; Wiles, Keith
>> <keith.wiles@intel.com>; stephen@networkplumber.org
>> Subject: Re: [dpdk-dev] [PATCH v2 3/4] common_base: extend RTE_MAX_ETHPORTS from 32 to 1024
>>
>> Hi, Bruce:
>>
>>> -----Original Message-----
>>> From: Richardson, Bruce
>>> Sent: Monday, September 4, 2017 5:09 PM
>>> To: Yang, Zhiyong <zhiyong.yang@intel.com>
>>> Cc: Yao, Lei A <lei.a.yao@intel.com>; dev@dpdk.org; thomas@monjalon.net;
>>> Yigit, Ferruh <ferruh.yigit@intel.com>; Wiles, Keith <keith.wiles@intel.com>;
>>> stephen@networkplumber.org
>>> Subject: Re: [dpdk-dev] [PATCH v2 3/4] common_base: extend
>>> RTE_MAX_ETHPORTS from 32 to 1024
>>>>>> --- a/config/common_base
>>>>>> +++ b/config/common_base
>>>>>> @@ -131,7 +131,7 @@ CONFIG_RTE_LIBRTE_KVARGS=y  #
>>>>>> CONFIG_RTE_LIBRTE_ETHER=y  CONFIG_RTE_LIBRTE_ETHDEV_DEBUG=n
>>>>>> -CONFIG_RTE_MAX_ETHPORTS=32
>>>>>> +CONFIG_RTE_MAX_ETHPORTS=1024
>>>>>>  CONFIG_RTE_MAX_QUEUES_PER_PORT=1024
>>>>>>  CONFIG_RTE_LIBRTE_IEEE1588=n
>>>>>>  CONFIG_RTE_ETHDEV_QUEUE_STAT_CNTRS=16
>>>>>> --
>>>>>> 2.13.3
>>>>> Hi, Zhiyong
>>>>>
>>>>> I met one issue for changing CONFIG_RTE_MAX_ETHPORTS to 1024.
>>>>> One process can only open 1024 file as maximum in common linux
>>>>> distribution, after practice, only 1009 socket file can be used for
>>>>> vdev device with testpmd sample.
>>>>
>>>> Thanks for your info.  It seems that 1024 is too large and may bring some
>>> potential issues.
>>>>
>>>> Thanks
>>>> Zhiyong
>>>>
>>>
>>> It should be possible to have a dynamically allocated ethdev array, which would
>>> allow use to have a default value - which could be e.g. 32 or 64 as now - while
>>> also allowing a run-time parameter to increase that to thousands if needed.
>>>
>>> /Bruce
>>
>> In testpmd,  the following function will be called to validate the port_id.
>> So, It is necessary to modify the max port num RTE_MAX_ETHPORTS.
>
> There are quite a lot memory allocations (both static an dynamic) inside DPDK libs and sample apps
>  that use RTE_MAX_ETHPORTS.
> Increasing RTE_MAX_ETHPORTS would increase DPDK memory requirements quite significantly.

It is not a good idea to significantly increase the DPDK memory 
requirement.

Can you not make it with "CONFIG_RTE_MAX_ETHPORTS=1024" for your testing 
configs?

> Why do you think it is *necessary* to increase default RTE_MAX_ETHPORTS to 1024?
> Konstantin
>
>>
>> I think that RTE_MAX_ETHPORTS and  a default value(num of port ) should be different values.
>> Now dpdk limits the max num to RTE_MAX_ETHPORTS = 32 by default.
>> int
>> rte_eth_dev_is_valid_port(uint16_t port_id)
>> {
>> 	if (port_id >= RTE_MAX_ETHPORTS ||
>> 	    (rte_eth_devices[port_id].state != RTE_ETH_DEV_ATTACHED &&
>> 	     rte_eth_devices[port_id].state != RTE_ETH_DEV_DEFERRED))
>> 		return 0;
>> 	else
>> 		return 1;
>> }
>>
>> Thanks
>> Zhiyong.
>