[dpdk-dev] [PATCH v3] ethdev: add IPv4 and L4 checksum RSS offload types

[Andrew Rybchenko]

On 7/6/21 10:18 AM, Zhang, Qi Z wrote:
> 
> 
>> -----Original Message-----
>> From: Zhang, AlvinX <alvinx.zhang at intel.com>
>> Sent: Tuesday, July 6, 2021 3:06 PM
>> To: Andrew Rybchenko <andrew.rybchenko at oktetlabs.ru>; Zhang, Qi Z
>> <qi.z.zhang at intel.com>; ajit.khaparde at broadcom.com
>> Cc: dev at dpdk.org
>> Subject: RE: [PATCH v3] ethdev: add IPv4 and L4 checksum RSS offload types
>>
>>>> @@ -537,6 +537,8 @@ struct rte_eth_rss_conf {
>>>>  #define ETH_RSS_PPPOE		   (1ULL << 31)
>>>>  #define ETH_RSS_ECPRI		   (1ULL << 32)
>>>>  #define ETH_RSS_MPLS		   (1ULL << 33)
>>>> +#define ETH_RSS_IPV4_CHKSUM	   (1ULL << 34)
>>>> +#define ETH_RSS_L4_CHKSUM	   (1ULL << 35)
>>>
>>> What does efine which L4 protocols are supported? How user will know?
>>
>> I think if we want to support L4 checksum RSS by using below command port
>> config all rss (all|default|eth|vlan|...)
>>
>> We must define TCP/UDP/SCTP checksum RSS separately:
>> #define ETH_RSS_TCP_CHKSUM	(1ULL << 35)
>> #define ETH_RSS_UDP_CHKSUM	(1ULL << 36)
>> #deifne ETH_RSS_SCTP_CHKSUM	(1ULL << 37)
>>
>> Here 3 bits are occupied, this is not good for there are not many bits available.
>>
>> If we only want to using it in flows, we only need to define
>> ETH_RSS_L4_CHKSUM, because the flow pattern pointed out the L4 protocol
>> type.
>> flow create 0 ingress pattern eth / ipv4 / tcp / end actions rss types l4-chksum
>> end queues end / end
> 
> +1, the pattern already give the hint to avoid the ambiguity and I think we already have ETH_RSS_LEVEL to figure out inner or outer.

The problem that it may be used in generic RSS flags which
has no the context. Also even in the case of flow API
context could have no L4 protocol at all.

Is UDP checksum 0 treated as no checksum and go to default
queue or treated as a regular checksum with value equal to 0?

I tend to agree that 3 flags is too much for the feature,
but one flag without properly defined meaning is not good
as well.

I just want rules to be defined and documented.