Re: [dpdk-dev] [PATCH 2/2] net/tap: allow RSS flow action

[Pascal Mazon <pascal.mazon@6wind.com>]

Hi,

I was a little too quick earlier. The line breaks are justified because
they follow the list of variable declarations.

So I ack the whole patch series.

Acked-by: Pascal Mazon <pascal.mazon@6wind.com>

On 04/10/2017 10:19, Pascal Mazon wrote:
> Hi,
>
> What you say stands to reason, I'm basically ok with your patch, except
> for one remark.
> The rest of the file has no line breaks anywhere, please remove the two
> you added.
>
> Best regards,
> Pascal
>
> On 03/10/2017 16:55, Matan Azrad wrote:
>> One of the main identified use cases for the tap PMD is to be used in
>> combination with the fail-safe PMD as a fallback for a physical device.
>>
>> Fail-safe is very strict about making sure its current configuration is
>> properly applied to all slave devices, they get rejected otherwise in
>> order to maintain a consistent state.
>>
>> The problem is that tap's RSS support is currently limited to the
>> default (non-Toeplitz) balancing performed by the kernel on all Rx
>> queues. While proper RSS support emulation in the tap PMD is a work in
>> progress, the lack of rte_flow counterpart prevents validation of the
>> above use case in the meantime.
>>
>> Given that unlike most PMDs, tap is more about convenience than
>> performance, support for the RSS action can be temporarily faked with
>> a minimum amount of code and mostly correct behavior by treating it
>> like a QUEUE action. Traffic is directed to the first queue of the set.
>>
>> Signed-off-by: Matan Azrad <matan@mellanox.com>
>> ---
>>  drivers/net/tap/tap_flow.c | 15 +++++++++++++++
>>  1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
>> index aa33960..28d793f 100644
>> --- a/drivers/net/tap/tap_flow.c
>> +++ b/drivers/net/tap/tap_flow.c
>> @@ -1089,6 +1089,7 @@ struct tap_flow_items {
>>  			const struct rte_flow_action_queue *queue =
>>  				(const struct rte_flow_action_queue *)
>>  				actions->conf;
>> +
>>  			if (action)
>>  				goto exit_action_not_supported;
>>  			action = 1;
>> @@ -1097,6 +1098,20 @@ struct tap_flow_items {
>>  				goto exit_action_not_supported;
>>  			if (flow)
>>  				err = add_action_skbedit(flow, queue->index);
>> +		} else if (actions->type == RTE_FLOW_ACTION_TYPE_RSS) {
>> +			/* Fake RSS support. */
>> +			const struct rte_flow_action_rss *rss =
>> +				(const struct rte_flow_action_rss *)
>> +				actions->conf;
>> +
>> +			if (action)
>> +				goto exit_action_not_supported;
>> +			action = 1;
>> +			if (!rss || rss->num < 1 ||
>> +			    (rss->queue[0] > pmd->dev->data->nb_rx_queues - 1))
>> +				goto exit_action_not_supported;
>> +			if (flow)
>> +				err = add_action_skbedit(flow, rss->queue[0]);
>>  		} else {
>>  			goto exit_action_not_supported;
>>  		}