Re: [dpdk-dev] [PATCH v5] app/testpmd: fix the default RSS key configuration

[oulijun <oulijun@huawei.com>]

在 2020/10/20 18:02, Ferruh Yigit 写道:
> On 10/20/2020 10:00 AM, oulijun wrote:
>>
>>
>> 在 2020/10/16 18:57, Ferruh Yigit 写道:
>>> On 10/16/2020 11:04 AM, oulijun wrote:
>>>>
>>>>
>>>> 在 2020/10/16 7:53, Ferruh Yigit 写道:
>>>>> On 10/16/2020 12:21 AM, Ophir Munk wrote:
>>>>>>> From: Ferruh Yigit <ferruh.yigit@intel.com>
>>>>>>>>>> On 10/15/2020 1:41 PM, Lijun Ou wrote:
>>>>>>>>>>> When start the testpmd, the pmd driver initializes the RSS
>>>>>>>>>>> configuration. Generally, the recommended RSS hash key is 
>>>>>>>>>>> used as
>>>>>>>>>>> the default key in the driver. In addition, the default key is
>>>>>>>>>>> different from the default RSS flow in testpmd without 
>>>>>>>>>>> specifying
>>>>>>>>>>> RSS hash key. So. if you do not specify the RSS key when 
>>>>>>>>>>> creating
>>>>>>>>>>> an RSS rule, the testpmd uses the default key as the default RSS
>>>>>>>>>>> key of the RSS rule. As a result, you may mistakenly consider 
>>>>>>>>>>> that
>>>>>>>>>>> the RSS key in use is the valid default key of the NIC, 
>>>>>>>>>>> actually,
>>>>>>>>>>> the key and the valid default key of the NIC are two values.
>>>>>>>>>>>
>>>>>>>>>>> Consider the follow usage with testpmd:
>>>>>>>>>>> 1. first, startup testpmd:
>>>>>>>>>>> testpmd> show port 0 rss-hash key
>>>>>>>>>>> RSS functions:
>>>>>>>>>>>     all ipv4-frag ipv4-other ipv6-frag ipv6-other ip RSS key:
>>>>>>>>>>> -
>>>>>>> 6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA3803
>>>>>>> 0F
>>>>>>>>>>> -20C6A42B73BBEAC01FA
>>>>>>>>>>> 2. create a rss rule
>>>>>>>>>>> testpmd> flow create 0 ingress pattern eth / ipv4 / udp / end
>>>>>>>>>>> testpmd> actions rss \
>>>>>>>>>>> types ipv4-udp end queues end / end
>>>>>>>>>>>
>>>>>>>>>>> 3. show rss-hash key
>>>>>>>>>>> testpmd> show port 0 rss-hash key
>>>>>>>>>>> RSS functions:
>>>>>>>>>>>     all ipv4-udp udp
>>>>>>>>>>> RSS key:
>>>>>>>>>>> -
>>>>>>> 74657374706D6427732064656661756C74205253532068617368206B65792C
>>>>>>> 206F
>>>>>>>>>>> -76657272696465
>>>>>>>>>>>
>>>>>>>>>>> In order to solve the above problems, it use the NIC valid 
>>>>>>>>>>> default
>>>>>>>>>>> RSS key instead of the testpmd dummy RSS key in the flow
>>>>>>>>>>> configuration when the RSS key is not specified in the flow 
>>>>>>>>>>> rule.
>>>>>>>>>>> If the NIC RSS key is invalid, it will use testpmd dummy RSS 
>>>>>>>>>>> key as the
>>>>>>> default key.
>>>>>>>>>>>
>>>>>>>>>>> Fixes: ac8d22de2394 ("ethdev: flatten RSS configuration in flow
>>>>>>>>>>> API")
>>>>>>>>>>> Cc: stable@dpdk.org
>>>>>>>>>>>
>>>>>>>>>>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
>>>>>>>>>>> Reviewed-by: Phil Yang <phil.yang@arm.com>
>>>>>>>>>>> ---
>>>>>>>>>>> V4->V5:
>>>>>>>>>>> -rewrite the commit log
>>>>>>>>>>> -add reviewed-by
>>>>>>>>>>
>>>>>>>>>> Hi Lijun,
>>>>>>>>>>
>>>>>>>>>> There were multiple other comments, it seems they are not 
>>>>>>>>>> addressed
>>>>>>>>>> but only updated the commit log, can you please check comments to
>>>>>>> prev versions.
>>>>>>>>>>
>>>>>>>>>> Before going into the details, my question was what happens if
>>>>>>>>>> default key not provided at all?
>>>>>>>>>> It seems this has been already tried by Ophir [1], later reverted
>>>>>>>>>> back [2] bringing the initial issue back.
>>>>>>>>>>
>>>>>>>>>> According commit, the reason of revert is to support following
>>>>>>> command:
>>>>>>>>>> "flow create 0 <pattern> actions rss queues 0 1 end key_len 40 
>>>>>>>>>> / end"
>>>>>>>>>>
>>>>>>>>>> @Ophir, @Lijun,
>>>>>>>>>> Can we ignore the 'key_len' if the 'key' is not supported and 
>>>>>>>>>> solve
>>>>>>>>>> current issue as initially intended ([1])?
>>>>>>>>>>
>>>>>>>>> Hi, Ferruh
>>>>>>>>>     I have discussed with Phil Yang about the problem in [1]. I 
>>>>>>>>> think
>>>>>>>>> there may be other problems with the idea and there is no better
>>>>>>>>> solution. and we need to remove key_len definition from 
>>>>>>>>> rte_rss_conf
>>>>>>>>> structure. They don't have a plan. And [1] was eventually 
>>>>>>>>> reverted.
>>>>>>>>>
>>>>>>>>
>>>>>>>> Why ignoring 'key_len' (set it to zero) when there is no 'key'
>>>>>>>> provided doesn't work?
>>>>>>>>
>>>>>>>
>>>>>>> What do you think [1] + following update, will it work?
>>>>>>>
>>>>>>>    diff --git a/lib/librte_ethdev/rte_flow.c 
>>>>>>> b/lib/librte_ethdev/rte_flow.c
>>>>>>>    index ee4f3464fe..e7789c87b3 100644
>>>>>>>    --- a/lib/librte_ethdev/rte_flow.c
>>>>>>>    +++ b/lib/librte_ethdev/rte_flow.c
>>>>>>>    @@ -535,7 +535,7 @@ rte_flow_conv_action_conf(void *buf, const 
>>>>>>> size_t
>>>>>>> size,
>>>>>>>                               }),
>>>>>>>                               size > sizeof(*dst.rss) ? 
>>>>>>> sizeof(*dst.rss) : size);
>>>>>>>                    off = sizeof(*dst.rss);
>>>>>>>    -               if (src.rss->key_len) {
>>>>>>>    +               if (src.rss->key_len && src.rss->key) {
>>>>>>>                            off = RTE_ALIGN_CEIL(off, 
>>>>>>> sizeof(*dst.rss->key));
>>>>>>>                            tmp = sizeof(*src.rss->key) * 
>>>>>>> src.rss->key_len;
>>>>>>>                            if (size >= off + tmp)
>>>>>>>
>>>>>>
>>>>>> Ferruh, your suggestion ([1] + update) looks correct. I also 
>>>>>> verified it on mlx5 PMD.
>>>>>> Advantage: it's a generic fix for all dpdk applications using 
>>>>>> rte_flows (not just testpmd).
>>>>>> It reduces code.
>>>>>> With this fix the responsibility of handling key==NULL and/or 
>>>>>> len==0 is moved to the PMDs (which is good).
>>>>>> With regard to Lijun patch - I liked the approach of overriding 
>>>>>> the default testpmd key with the default PMD key.
>>>>>> But it only addresses testpmd. More code was added.
>>>>>> It seems OK to call rte_eth_dev_rss_hash_conf_get() as part of 
>>>>>> parsing RSS, but it would feel more confident if we could confirm 
>>>>>> it for all the PMDs (by testing) or at least review the PMDs 
>>>>>> rss_hash_conf_get() implementations.
>>>>>>
>>>>>
>>>>> Lijun's idea can work. There was a problem in implementation 
>>>>> related to the key size assumption, which can be fixed.
>>>>>
>>>>> Even it is fixed, when user gives a rss rule without a key, we are 
>>>>> getting key from device and feeding same key back to device, this 
>>>>> is unnecessary I think.
>>>>> When user didn't provide a key, rss rule shouldn't touch the key at 
>>>>> all.
>>>>>
>>>> Do you mean that the driver should not configure the key to the 
>>>> hardware when the RSS key is not specified?
>>>
>>> We are talking about 'key' in RSS rte flow rule, not generally 
>>> configuring the device for RSS.
>>>
>> Yes, I know. However, I am talking about some implementations. The 
>> configuration interface may be the same as that for configuring RSS
>> parameters of the device in general mode.
>>> If a specific rss rte flow rule, lets say to filter some defined 
>>> packets to some specific queues, don't have 'key' as a part of rule, 
>>> I am suggesting not touch 'key' configuration of the device.
>>>
>> Yes, I agree. I think your point of view is very reasonable and a more
>> appropriate implementation. However, for the sake of simplicity and
>> other considerations in the architecture design of some devices, the
>> hardware may support reasonable hybrid configuration for paramter 
>> configuration in the RSS config, rather than independent configuration
>> for hw, that is, maybe touch A of rss configuration of the device and
>> must touch B of rss configuration. As a result, If the preceding 
>> scenario occurs, it is reasonable to configure an RSS config that does 
>> not change and specified.What do you think?
>>>> If so, we cannot identify when the user does not specify the RSS key 
>>>> to determine whether to configure the key.
>>>
>>> I think we can. If the rule has 'key' attribute, driver can use that 
>>> key to program the device, if 'key' attribute is missing, don't do 
>>> anything related to the rss key.
>>>
>> Yes, if 'key' attribute is missing, don't do anything related to the 
>> rss key. It's more reasonable.
>> But, If he can't do that, I think it is reasonable to configure the 
>> default key that already exists on the device. The only disadvantage 
>> is wasteful.
>>>> In hardware design, most vendors do not configure keys for hardware 
>>>> independently, which may be associated with other RSS config 
>>>> parameters.
>>>> I think it would be reasonable for us to reconfigure the RSS key 
>>>> with the default value configured and valid in the hardware as the 
>>>> default value if the user does not specify the RSS key.
>>>
>>> There are already APIs to update the RSS configuration, like RSS key, 
>>> hash functions etc.. They are independent from the rte flow RSS rule.
>>> Application should configure RSS according needs using those APIs.
>>>
>> Yes, should do this. Are there any unreasonable users who simply do 
>> not know these APIs or do not want to use them and want to configure 
>> some parameters through the rte flow RSS rule without changing other 
>> parameters?
>>> The question here is about each RSS rte flow rule that can update the 
>>> key. Am I missing something?
>> I don't think you've misunderstood the general situation.
>> Even if the RSS key is not specified in a rule, the driver uses the 
>> default key value to re-touch the device.
>>>
>>>>> Complication was when user provides key_len without a key, I think 
>>>>> both ignoring or returning error in this case is OK.
>>>> I agree. However, I think it is meaningless to expose the RSS key 
>>>> length to users. Do you consider deleting the RSS key length directly?
>>>
>>> Isn't both 'key' and 'key_len' needed to program the RSS key? Can the 
>>> driver know the size of the 'key' without 'key_len'?
>>> And driver should verify these provided values.
>>>
>> I know and agree.It is only during the analysis of the [1] scheme, 
>> from the time it was proposed to the time it was withdrawn, that I 
>> found some guys in the community questioned the significance of key_len.
>>
>> Back to the subject, what is your plan for the solution in the patch?
> 
> I think, Ophir's old reverted patch [1] + 'rte_flow_conv_action_conf()' 
> update I proposed above can work. Is this working for you? If so can you 
> please send a patch?
> 
> 
> [1] https://git.dpdk.org/dpdk/commit/?id=a4391f8bae8
> .
Hi, Ferruh
    I've just used [1] + 'rte_flow_conv_action_conf()' for testing based 
on the Kunpeng920 NIC plation and use hns3 pmd driver. it can be resolve 
the RSS key question.
    testpmd> show port 0 rss-hash key
RSS functions:
  all ipv4-frag ipv4-other ipv6-frag ipv6-other ip
RSS key:
6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA
testpmd> flow create 0 ingress pattern end actions rss func 
symmetric_toeplitz types all end / end
0000:7d:00.0 hns3_config_rss_filter(): modified RSS types based on 
hardware support, requested:7f83fffc configured:3ef8
0000:7d:00.0 hns3_parse_rss_key(): no valid RSS key config, using default
Flow rule #0 created
testpmd> show port 0 rss-hash key
RSS functions:
  all ipv4-frag ipv4-tcp ipv4-udp ipv4-sctp ipv4-other ipv6-frag 
ipv6-tcp ipv6-udp ipv6-sctp ipv6-other ip udp tcp sctp
RSS key:
6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA

However, I also tested the case. I am not specified the RSS key and 
specified the key_len when create a RSS flow rule, it can create success.
testpmd> flow create 0 ingress pattern end actions rss queues 0 1 end 
key_len 40 / end
0000:7d:00.0 hns3_config_rss_filter(): modified RSS types based on 
hardware support, requested:a38c configured:2288
0000:7d:00.0 hns3_parse_rss_key(): no valid RSS key config, using default
Flow rule #0 created
testpmd> show port 0 rss-hash key
RSS functions:
  all ipv4-frag ipv4-other ipv6-frag ipv6-other ip
RSS key:
6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA

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