[dpdk-dev] i40e: disabling flow control makes XL710 NIC discard all packets

[dpdk-dev] i40e: disabling flow control makes XL710 NIC discard all packets

[Martin Weiser]

Hi Helin,

I have been doing some tests with the current DPDK master to see if the
issues we had with performance and statistics have improved.
In our own applications we usually disable flow control using the
following code:

struct rte_eth_fc_conf fc_conf = { .mode = RTE_FC_NONE };
int ret = rte_eth_dev_flow_ctrl_set(port_id, &fc_conf);

In DPDK 2.1 this did not cause any problems with XL710 NICs but with the
current master the NIC will not receive any packets and they are all
counted in ierrors and imissed.
The return value of rte_eth_dev_flow_ctrl_set does not indicate an error
so it seems like something is going wrong here.

Regards,
Martin

Re: [dpdk-dev] i40e: disabling flow control makes XL710 NIC discard all packets

[Zhang, Helin]

Hi Martin

Thank you very much for reporting the issue!
Could you help to add more detailed steps and other information?
We will try to reproduce what have seen in our lab, and then debug.

Regards,
Helin

> -----Original Message-----
> From: Martin Weiser [mailto:martin.weiser@allegro-packets.com]
> Sent: Wednesday, November 4, 2015 6:17 PM
> To: Zhang, Helin; dev@dpdk.org
> Subject: i40e: disabling flow control makes XL710 NIC discard all packets
> 
> Hi Helin,
> 
> I have been doing some tests with the current DPDK master to see if the issues
> we had with performance and statistics have improved.
> In our own applications we usually disable flow control using the following code:
> 
> struct rte_eth_fc_conf fc_conf = { .mode = RTE_FC_NONE }; int ret =
> rte_eth_dev_flow_ctrl_set(port_id, &fc_conf);
> 
> In DPDK 2.1 this did not cause any problems with XL710 NICs but with the current
> master the NIC will not receive any packets and they are all counted in ierrors and
> imissed.
> The return value of rte_eth_dev_flow_ctrl_set does not indicate an error so it
> seems like something is going wrong here.

> 
> Regards,
> Martin

Re: [dpdk-dev] i40e: disabling flow control makes XL710 NIC discard all packets

[Martin Weiser]

Hi Helin,

I did some more testing and it seems like the issue is triggered when
the 'high_water' and 'low_water' fields of the 'rte_eth_fc_conf'
structure are set to 0 (like in my initial code example).
The following example does not trigger the issue:

struct rte_eth_fc_conf fc_conf;
rte_eth_dev_flow_ctrl_get(pi, &fc_conf);
fc_conf.mode = RTE_FC_NONE;
rte_eth_dev_flow_ctrl_set(pi, &fc_conf);

But when using the following code all packets will be discarded although
the call to rte_eth_dev_flow_ctrl_set does not return an error:

struct rte_eth_fc_conf fc_conf;
rte_eth_dev_flow_ctrl_get(pi, &fc_conf);
fc_conf.mode = RTE_FC_NONE;
fc_conf.low_water = 0;
fc_conf.high_water = 0;
rte_eth_dev_flow_ctrl_set(pi, &fc_conf);

I think the rest of the structure's values should not have any effect as
long as flow control is completely disabled by setting the mode to
RTE_FC_NONE. At least it did not with DPDK 2.1 or for other NIC types.

Regards,
Martin


On 04.11.15 15:32, Zhang, Helin wrote:
> Hi Martin
>
> Thank you very much for reporting the issue!
> Could you help to add more detailed steps and other information?
> We will try to reproduce what have seen in our lab, and then debug.
>
> Regards,
> Helin
>
>> -----Original Message-----
>> From: Martin Weiser [mailto:martin.weiser@allegro-packets.com]
>> Sent: Wednesday, November 4, 2015 6:17 PM
>> To: Zhang, Helin; dev@dpdk.org
>> Subject: i40e: disabling flow control makes XL710 NIC discard all packets
>>
>> Hi Helin,
>>
>> I have been doing some tests with the current DPDK master to see if the issues
>> we had with performance and statistics have improved.
>> In our own applications we usually disable flow control using the following code:
>>
>> struct rte_eth_fc_conf fc_conf = { .mode = RTE_FC_NONE }; int ret =
>> rte_eth_dev_flow_ctrl_set(port_id, &fc_conf);
>>
>> In DPDK 2.1 this did not cause any problems with XL710 NICs but with the current
>> master the NIC will not receive any packets and they are all counted in ierrors and
>> imissed.
>> The return value of rte_eth_dev_flow_ctrl_set does not indicate an error so it
>> seems like something is going wrong here.
>> Regards,
>> Martin