Re: [PATCH 1/2] ethdev: add Rx packet type offload control flag

[Ferruh Yigit <ferruh.yigit@amd.com>]

On 9/24/2024 3:03 AM, Chaoyong He wrote:
>> On 6/19/2024 11:11 AM, Chaoyong He wrote:
>>> From: Long Wu <long.wu@corigine.com>
>>>
>>> The Rx packet type offload feature may affect the performance, so add
>>> a control flag for applications to turn it on or off.
>>>
>>> Signed-off-by: Long Wu <long.wu@corigine.com>
>>> ---
>>>  lib/ethdev/rte_ethdev.h | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h index
>>> 548fada1c7..be86983e24 100644
>>> --- a/lib/ethdev/rte_ethdev.h
>>> +++ b/lib/ethdev/rte_ethdev.h
>>> @@ -1555,6 +1555,7 @@ struct rte_eth_conf {  #define
>>> RTE_ETH_RX_OFFLOAD_OUTER_UDP_CKSUM  RTE_BIT64(18)
>>>  #define RTE_ETH_RX_OFFLOAD_RSS_HASH         RTE_BIT64(19)
>>>  #define RTE_ETH_RX_OFFLOAD_BUFFER_SPLIT     RTE_BIT64(20)
>>> +#define RTE_ETH_RX_OFFLOAD_PTYPES           RTE_BIT64(21)
>>>
>>>  #define RTE_ETH_RX_OFFLOAD_CHECKSUM
>> (RTE_ETH_RX_OFFLOAD_IPV4_CKSUM | \
>>>  				 RTE_ETH_RX_OFFLOAD_UDP_CKSUM | \
>>
>> Hi Chaoyong,
>>
>> Instead of having an offload for ptypes, we have APIs for this,
>>
>> First one is 'rte_eth_dev_get_supported_ptypes()' that application can learn
>> the supported packet types.
>>
>> Second one is more related to above flag, it is 'rte_eth_dev_set_ptypes()'
>> which application can set which pytpes is required, it can be set to disable all
>> packet type parsing, can be similar to not requesting
>> 'RTE_ETH_RX_OFFLOAD_PTYPES'.
>>
>> With above two APIs, do we still need the offload flag?
>>
> 
> At present, the purpose of the ops 'rte_eth_dev_set_ptypes()' is to set the range of packet types to handle.
>

Yes, and setting 'ptype_mask' to zero should disable packet type parsing.

Packet type parsing is an offload, but when we have an API that has
finer grained control to what packet type to parse, why not use it
instead of having offload flag, which is all on or off configuration.

> Of course, we can maintain a flag for each application and driver based on the return value of this ops;
> but this is a bit troublesome.
>

I didn't get your point, why maintain a flag?

> So, we hope to follow the example of RSS, in addition to
> 'rte_eth_dev_rss_hash_update()' and 'rte_eth_dev_rss_hash_conf_get()', we also want to set a flag for
> the ptype function similar to RTE_ETH_RX_OFFLOAD_RSS_HASH.
> 
>>
>> Another concern with adding new offload flag is backward compatibility, all
>> existing drivers that support packet type parsing should be updated to list this
>> offload flag as capability. Also they need to be updated to configure packet
>> parsing based on user requested offload configuration.
>>
> 
> If you agree with this design suggestion, we will adapt all the related code to ptypes for each PMDs and 'test-pmd' applications in the next patch.
> Do you think this okay?
> 
>> Briefly, we can't just introduce a new offload flag for an existing capability and
>> update only one driver, all drivers needs to be updated.