From: Ferruh Yigit <ferruh.yigit@amd.com>
To: Jerin Jacob <jerinjacobk@gmail.com>
Cc: Thomas Monjalon <thomas@monjalon.net>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
Ori Kam <orika@nvidia.com>,
Ivan Malov <ivan.malov@arknetworks.am>,
Nithin Kumar Dabilpuram <ndabilpuram@marvell.com>,
Aman Singh <aman.deep.singh@intel.com>,
Yuying Zhang <yuying.zhang@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>,
Hanumanth Reddy Pothula <hpothula@marvell.com>,
Slava Ovsiienko <viacheslavo@nvidia.com>,
Jerin Jacob Kollanukkaran <jerinj@marvell.com>,
"david.marchand@redhat.com" <david.marchand@redhat.com>
Subject: Re: [EXT] Re: [PATCH v5 2/2] app/testpmd: add command to process Rx metadata negotiation
Date: Thu, 2 Feb 2023 08:43:12 +0000 [thread overview]
Message-ID: <bfc0cc12-4255-6986-cee5-1015d86f2421@amd.com> (raw)
In-Reply-To: <CALBAE1OaFQbm1XSmgoQx=sytAbepGDgy7rcxa2rMjHgLsmAOgw@mail.gmail.com>
On 2/1/2023 3:22 PM, Jerin Jacob wrote:
> On Wed, Feb 1, 2023 at 8:20 PM Ferruh Yigit <ferruh.yigit@amd.com> wrote:
>>
>> On 2/1/2023 1:48 PM, Jerin Jacob wrote:
>>> On Wed, Feb 1, 2023 at 5:06 PM Ferruh Yigit <ferruh.yigit@amd.com> wrote:
>>>>
>>>> On 2/1/2023 11:15 AM, Jerin Jacob wrote:
>>>>> On Wed, Feb 1, 2023 at 4:35 PM Thomas Monjalon <thomas@monjalon.net> wrote:
>>>>>>
>>>>>> 01/02/2023 11:58, Andrew Rybchenko:
>>>>>>> On 2/1/23 13:48, Jerin Jacob wrote:
>>>>>>>> On Wed, Feb 1, 2023 at 2:59 PM Andrew Rybchenko
>>>>>>>> <andrew.rybchenko@oktetlabs.ru> wrote:
>>>>>>>>> Frankly speaking I don't understand why default value is so
>>>>>>>>> important if we have a way to change it. Reasons should be
>>>>>>>>> really strong to change existing defaults.
>>>>>>>>
>>>>>>>> The only reason is, typically testpmd will be used performance
>>>>>>>> benchmarking as an industry standard. It is difficult to tell/educate
>>>>>>>> the QA or customers
>>>>>>>> that, "BTW if you need to get better performance add more flag to
>>>>>>>> testpmd command line".
>>>>>>
>>>>>> I disagree.
>>>>>> When you do performance benchmark, you tune settings accordingly.
>>>>>
>>>>> IMO, We tune the system resources like queue depth not the disabling
>>>>> features for raw performance.
>>>>> queue depth etc people know to tune so it is obvious. What is not
>>>>> obvious is, testpmd only
>>>>> negotiated some features by default.I am not using that feature, hence
>>>>> I need to explicitly
>>>>> disable it.
>>>>>
>>>>
>>>> When 'rte_eth_rx_metadata_negotiate()' API is NOT used at all, and I
>>>> believe that is the case for almost all applications since API is a
>>>> relatively new one, PMD default behavior should be to enable Rx metadata
>>>> flow rules, in case user requests them later.
>>>>
>>>> So, enabling all in application is same with not calling the API at all.
>>>>
>>>> In this perspective, disabling Rx metadata is additional
>>>> optimization/tuning that application can do if it is sure that Rx
>>>> metadata flow rules won't be used at all.
>>>> And API is more meaningful when it is used to disable Rx metadata.
>>>>
>>>> I think it is reasonable to enable all Rx metadata by default in testpmd
>>>> with a capability to disable it when wanted.
>>>>
>>>> OR
>>>>
>>>> May be we don't call 'rte_eth_rx_metadata_negotiate()' API by default in
>>>> testpmd, it is only called when it is requested explicitly from user,
>>>> enable or disable.
>>>
>>> Second option looks good to me.
>>> When
>>> 1) user request for action which is needed negotiate(),
>>> AND
>>> 2) rte_eth_rx_metadata_negotiate() != ENOSUP
>>> then, testpmd print a warning that need to enable
>>> rte_eth_rx_metadata_negotiate().
>>>
>>
>> We are not suggesting same thing.
>>
>> What you described above assumes PMD disabled Rx metadata flow rule
>> support by default, and it needs to be enabled explicitly by
>> 'rte_eth_rx_metadata_negotiate()' API. This API becomes mandatory for
>> functionality.
>>
>> As far as I understand PMD wants to disable this flow rule by default
>> because of performance concerns. But this creates inconsistency between
>> PMDs, because rest of them will enable this flow rule by default (if it
>> is supported) and be ready to use it when proper flow rule created.
>>
>> With this approach some PMDs will need 'rte_eth_rx_metadata_negotiate()'
>> to enable Rx metadata flow rules, some won't. This can be confusing for
>> applications that *some* PMDs require double enabling with specific API
>> call.
>>
>>
>> Instead what I was trying to suggest is reverse,
>> all PMDs enable the Rx metadata flow rule by default, and don't require
>> double enabling.
>> But if application knows that it won't use Rx metadata flow rule, it can
>> disable it to optimize the performance.
>> This makes 'rte_eth_rx_metadata_negotiate()' functionally optional, and
>> for testpmd context it can be called via a command on demand by user for
>> optimization purpose.
>
> This won't solve concern I have outlined earlier[1].
>
Yes, it won't.
> I think, The part of the problem there is no enough adaption of
> rte_eth_rx_metadata_negotiate(),
>
> The view is total different from PMD maintainer PoV vs testpmd application PoV.
>
Agree,
and I assume it is different for user application too, which may
prioritize consistency and portability.
Overall, I am not fan of the 'rte_eth_rx_metadata_negotiate()' API, I
think it is confusing.
> Just to avoid back and forth. We will call off this patch and remove
> rte_eth_rx_metadata_negotiate()
> PMD callback from cnxk driver. Keep it as old behavior, so we don't need to care
> about rte_eth_rx_metadata_negotiate().
>
When you remove 'rx_metadata_negotiate' callback, what will be the PMD
behavior? I assume PMD will do the required preparations as if all Rx
metadata is enabled.
And what is the performance impact, is removing callback improve the
performance?
> [1]
> The only reason is, typically testpmd will be used performance
> benchmarking as an industry standard. It is difficult to tell/educate
> the QA or customers
> that, "BTW if you need to get better performance add more flag to
> testpmd command line".
> To make that worst, only some PMD needs to give the additional
> parameter to get better number.
> And also, testpmd usage will be treated as application modeling.
>
>>
>>
>>
>>
>>>
>>>>>
>>>>>>
>>>>>>>> To make that worst, only some PMD needs to give the additional
>>>>>>>> parameter to get better number.
>>>>>>>> And also, testpmd usage will be treated as application modeling.
>>>>>>>>
>>>>>>>> Since this feature only used on sfc and cnxk driver, What is the
>>>>>>>> situation with sfc driver?
>>>>>>>> Keeping it as negotiated and not use the feature, will impact the per
>>>>>>>> core performance of sfc or
>>>>>>>> is it just PCI bandwidth thing which really dont show any difference in testpmd?
>>>>>>>
>>>>>>> Yes, sfc could run faster if no Rx metadata are negotiated. So,
>>>>>>> it is better to negotiate nothing by default. But it is always
>>>>>>> painful to change defaults. You need to explain that now you
>>>>>>> need to negotiate Rx metadata to use mark, flag and tunnel offloads.
>>>>>>> Yes, it will be required on sfc and cnxk only.
>>>>>>> As an sfc maintainer I don't mind to change testpmd defaults.
>>>>>>
>>>>>> If we change testpmd defaults to "do nothing",
>>>>>> then we should disable MBUF_FAST_FREE as well.
>>>>>
>>>>> if you see MBUF_FAST_FREE, it does nothing. Actually,
>>>>> !MBUF_FAST_FREE is doing more work.
>>>>>
>>>>>
>>>>>>
>>>>>>
>>>>
>>
next prev parent reply other threads:[~2023-02-02 8:43 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-01 4:41 [PATCH] app/testpmd: add command line argument 'rx-metadata' Hanumanth Pothula
2022-08-01 13:11 ` Hanumanth Pothula
2022-08-01 13:13 ` Hanumanth Pothula
2022-08-01 19:41 ` Ivan Malov
2022-08-02 16:45 ` [PATCH] app/testpmd: add command line argument 'nic-to-pmd-rx-metadata' Hanumanth Pothula
2022-08-02 16:45 ` [PATCH v2 1/2] version: 22.11-rc0 Hanumanth Pothula
2022-08-02 16:45 ` [PATCH v2 2/2] app/testpmd: add command line argument 'nic-to-pmd-rx-metadata' Hanumanth Pothula
2022-08-02 17:51 ` [PATCH v2 1/1] " Hanumanth Pothula
2022-08-30 12:36 ` Hanumanth Reddy Pothula
2022-09-01 8:03 ` Singh, Aman Deep
2022-10-04 14:48 ` Andrew Rybchenko
2022-10-06 18:35 ` [PATCH v3 1/1] app/testpmd: control passing Rx metadata to PMD Hanumanth Pothula
2022-10-17 8:32 ` Andrew Rybchenko
2022-10-27 7:34 ` Thomas Monjalon
2022-10-27 12:54 ` Thomas Monjalon
2022-12-02 16:14 ` [EXT] " Hanumanth Reddy Pothula
2022-12-02 19:41 ` Thomas Monjalon
2022-12-05 7:59 ` Hanumanth Reddy Pothula
2022-12-05 8:28 ` Thomas Monjalon
2022-12-05 9:43 ` Slava Ovsiienko
2022-12-20 20:02 ` [PATCH v4 1/2] ethdev: control Rx metadata negotiation Hanumanth Pothula
2022-12-20 20:02 ` [PATCH v4 2/2] app/testpmd: add command to process " Hanumanth Pothula
2022-12-20 21:23 ` Stephen Hemminger
2022-12-21 2:07 ` [PATCH v5 1/2] ethdev: fix ethdev configuration state on reset Hanumanth Pothula
2022-12-21 2:07 ` [PATCH v5 2/2] app/testpmd: add command to process Rx metadata negotiation Hanumanth Pothula
2023-01-18 10:32 ` Thomas Monjalon
2023-01-19 10:33 ` [EXT] " Hanumanth Reddy Pothula
2023-01-25 12:51 ` Thomas Monjalon
2023-01-24 18:04 ` Ferruh Yigit
2023-01-25 9:30 ` [EXT] " Hanumanth Reddy Pothula
2023-01-25 12:55 ` Thomas Monjalon
2023-01-25 13:55 ` Ferruh Yigit
2023-01-25 13:59 ` Thomas Monjalon
2023-01-25 14:42 ` Nithin Kumar Dabilpuram
2023-01-26 11:03 ` Thomas Monjalon
2023-01-27 5:02 ` Nithin Kumar Dabilpuram
2023-01-27 8:54 ` Thomas Monjalon
2023-01-27 10:42 ` Nithin Kumar Dabilpuram
2023-01-27 15:01 ` Thomas Monjalon
2023-01-31 16:17 ` Jerin Jacob
2023-01-31 23:03 ` Thomas Monjalon
2023-02-01 6:10 ` Ivan Malov
2023-02-01 7:16 ` Andrew Rybchenko
2023-02-01 8:53 ` Jerin Jacob
2023-02-01 9:00 ` Ori Kam
2023-02-01 9:05 ` Thomas Monjalon
2023-02-01 9:07 ` Andrew Rybchenko
2023-02-01 9:14 ` Jerin Jacob
2023-02-01 9:29 ` Andrew Rybchenko
2023-02-01 10:48 ` Jerin Jacob
2023-02-01 10:58 ` Andrew Rybchenko
2023-02-01 11:04 ` Thomas Monjalon
2023-02-01 11:15 ` Jerin Jacob
2023-02-01 11:35 ` Ferruh Yigit
2023-02-01 13:48 ` Jerin Jacob
2023-02-01 14:50 ` Ferruh Yigit
2023-02-01 15:22 ` Jerin Jacob
2023-02-02 8:43 ` Ferruh Yigit [this message]
2023-02-02 8:50 ` Ivan Malov
2023-02-02 9:17 ` Ferruh Yigit
2023-02-02 10:41 ` Ivan Malov
2023-02-02 10:48 ` Ivan Malov
2023-02-02 11:41 ` Thomas Monjalon
2023-02-02 11:55 ` Ivan Malov
2023-02-02 12:03 ` Thomas Monjalon
2023-02-02 12:21 ` Andrew Rybchenko
2023-02-01 11:20 ` Ivan Malov
2023-01-25 13:17 ` Ferruh Yigit
2023-01-25 13:21 ` Ferruh Yigit
2023-01-25 13:21 ` Ferruh Yigit
2023-01-16 10:43 ` [PATCH v5 1/2] ethdev: fix ethdev configuration state on reset Hanumanth Reddy Pothula
2023-01-18 10:29 ` Thomas Monjalon
2023-01-24 18:14 ` Ferruh Yigit
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