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From: Shreyansh Jain <shreyansh.jain@nxp.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>
Cc: Bruce Richardson <bruce.richardson@intel.com>,
	"Horton, Remy" <remy.horton@intel.com>,
	 "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	 "Lu, Wenzhuo" <wenzhuo.lu@intel.com>,
	"Wu, Jingjing" <jingjing.wu@intel.com>,
	 "Zhang, Qi Z" <qi.z.zhang@intel.com>,
	"Xing, Beilei" <beilei.xing@intel.com>,
	 Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [dpdk-dev] [RFC PATCH v1 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters
Date: Wed, 21 Mar 2018 12:21:31 +0530	[thread overview]
Message-ID: <CAJ5mUsVZe7gjvHVRmqpzOni8r_+Dsun23M3j7trMj0GfF+Nrsg@mail.gmail.com> (raw)
In-Reply-To: <8af6d6ea-34d8-3b0d-cd34-c11ebb2a8207@intel.com>

On Tue, Mar 20, 2018 at 8:24 PM, Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> On 3/16/2018 1:54 PM, Shreyansh Jain wrote:
>> On Thu, Mar 15, 2018 at 8:27 PM, Ferruh Yigit <ferruh.yigit@intel.com> wrote:

[...]

>>> Hi Remy, Shreyansh,
>>>
>>> What do you think about using a variable name consistent with existing
>>> "default_[rt]xconf" in dev_info?
>>
>> It just turned out to be much more complex than I initially thought :)
>> Is this what the above conversation merging at (for Rx, as example):
>>
>> 1. 'default_rx_size_conf' is added in rte_eth_dev_info (and this
>> includes I/O  params like burst size, besides configure time nb_queue,
>> nb_desc etc). Driver would return these values filled in when
>> info_get() is called.
>>
>> 2a. If an application needs the defaults, it would perform info_get()
>> and get the values. then, use the values in configuration APIs
>> (rx_queue_setup for nb_rx_desc, eth_dev_dev_configure for
>> nb_rx_queues).
>> For rx_burst calls, it would use the burst_size fields obtained from info_get().
>> This is good enough for configuration and datapath (rx_burst).
>>
>> OR, another case
>>
>> 2b. Application wants to use default vaules provided by driver without
>> calling info_get. In which case, it would call
>> rx_queue_setup(nb_rx_desc=0..) or eth_dev_configure(nb_rx_queue=0,
>> nb_tx_queue=0). The implementation would query the value from
>> 'default_rx_size_conf' through info_get() and use those values.
>> Though, in this case, rte_eth_rx_burst(burst=0) might not work for
>> picking up the default within rte_ethdev.h.
>
> In Bruce's suggestion where ethdev keep defaults is changed.
> Initial suggestion was rte_eth_dev_info_get() filling default data, now defaults
> will be defined in functions like rte_eth_rx_queue_setup().
>
> This is a little different from filling defaults in rte_eth_dev_info_get():
> - Application can know where the defaults are coming from because dev_info
> fields are only modified by PMD. Application still prefer to use ethdev defaults.
>
> - The default values in ethdev library provided in function related to that
> data, instead of separate rte_eth_dev_info_get() function.

It seems we both are on same page (almost) - just that I couldn't
articulate my comments properly earlier, maybe.

rte_eth_dev_info_get is only a method to get defaults set by PMDs.
dev_info_get is not setting defaults by itself. I get this.

>
>
> What application can do:
> -  Application can call rte_eth_dev_info_get() and can learn if PMD provided
> defaults or not.
> - If PMD doesn't provided any default values application can prefer to use
> application defined values. This may be an option for the application looking
> for most optimized values.
> - Although PMD doesn't provide any defaults, application still can use defaults
> provided by ethdev by providing '0' as arguments.

Yes, agree - and only comment I added previously in this case is that
this is not applicable for burst APIs. So, optimal [rt]x burst size
cannot be 'defaulted' to EAL layer. Other values like ring size, queue
count can be delegated to EAL for overwriting if passed as '0'.

>
>
> So how related ethdev functions will be updated:
> if argument != 0
>   use argument
> else
>   dev_info_get()
>     if dev_info->argument != 0
>       use dev_info->argument
>     else
>       use function_prov

Perfect, but only for eth_dev_configure and eth_[rt]x_queue_setup functions -
and that is OK with me.

>
>>
>> :Four observations:
>> A). For burst size (or any other I/O time value added in future),
>> values would have to be explicitly used by application - always. If
>> value reported by info_get() is '0' (see (B) below), application to
>> use its own judgement. No default override by lib_eal.
>> IMO, This is good enough assumption.
>
> This is no more true after Bruce's comment.
> If application provides any values it will overwrite everything else,
> application has the final word.
> But application may prefer to use provided default values.

I am not sure what has changed with Bruce's comment - but I agree with
what you are stating.

>
>>
>> B). '0' as an indicator for 'no-default-value-available-from-driver'
>> is still an open point. It is good enough for current proposed
>> parameters, but may be a valid numerical value in future.
>> IMO, this can be ignored for now.
>
> Agree that we can ignore it for now.
>
>>
>> C) Unlike the original proposal, this would add two separate members
>> to rte_eth_dev_info - one each for Rx and Tx. They both are still
>> expected to be populated through the info_get() implementation but not
>> by lib_eal.
>> IMO, doesn't matter.
>
> There won't be new members, which ones are you talking about?

original proposal: (ignore change of names, please)

 rte_eth_dev_preferred_info {
     rx_burst_size
     tx_burst_size
     rx_ring_size
     tx_ring_size
     ...
  }

And this is what I think last few comments intended:

 rte_eth_rxpreferred {
   ...
   rx_burst_size
   rx_ring_size
   ...
 }

 rte_eth_txpreferred {
   ...
   tx_burst_size
   tx_ring_size
   ...
 }

both the above added rte_eth_dev_info{}

This is what I meant when I stated "...this would add two separate
members to rte_eth_dev_info - one each for Rx and Tx..."

[...]

-
Shreyansh

  reply	other threads:[~2018-03-21  6:52 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-07 12:08 [dpdk-dev] [RFC PATCH v1 0/4] ethdev: add per-PMD tuning of RxTx parmeters Remy Horton
2018-03-07 12:08 ` [dpdk-dev] [RFC PATCH v1 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters Remy Horton
2018-03-14 12:28   ` Shreyansh Jain
2018-03-14 14:09     ` Remy Horton
2018-03-14 14:43   ` Ferruh Yigit
2018-03-14 15:10     ` Shreyansh Jain
2018-03-15  9:02       ` Remy Horton
2018-03-14 15:48     ` Remy Horton
2018-03-14 16:42       ` Ferruh Yigit
2018-03-14 17:23         ` Shreyansh Jain
2018-03-14 17:52           ` Ferruh Yigit
2018-03-14 18:53             ` Ananyev, Konstantin
2018-03-14 21:02               ` Ferruh Yigit
2018-03-14 21:36                 ` Bruce Richardson
2018-03-15 13:57                   ` Ferruh Yigit
2018-03-15 14:39                     ` Bruce Richardson
2018-03-15 14:57                       ` Ferruh Yigit
2018-03-16 13:54                         ` Shreyansh Jain
2018-03-16 14:18                           ` Bruce Richardson
2018-03-16 15:36                           ` Remy Horton
2018-03-20 15:03                             ` Ferruh Yigit
2018-03-21 10:14                               ` Remy Horton
2018-03-21 13:56                                 ` Ferruh Yigit
2018-03-20 14:54                           ` Ferruh Yigit
2018-03-21  6:51                             ` Shreyansh Jain [this message]
2018-03-21 10:02                               ` Ferruh Yigit
2018-03-21 10:45                                 ` Shreyansh Jain
2018-03-15 12:51                 ` Ananyev, Konstantin
2018-03-15 13:57                   ` Ferruh Yigit
2018-03-15 14:42                     ` Bruce Richardson
2018-03-07 12:08 ` [dpdk-dev] [RFC PATCH v1 2/4] net/e1000: add TxRx tuning parameters Remy Horton
2018-03-07 12:08 ` [dpdk-dev] [RFC PATCH v1 3/4] net/i40e: " Remy Horton
2018-03-07 12:08 ` [dpdk-dev] [RFC PATCH v1 4/4] testpmd: make use of per-PMD TxRx parameters Remy Horton
2018-03-21 14:27 ` [dpdk-dev] [PATCH v2 0/4] ethdev: add per-PMD tuning of RxTx parmeters Remy Horton
2018-03-21 14:27   ` [dpdk-dev] [PATCH v2 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters Remy Horton
2018-03-28  7:11     ` Shreyansh Jain
2018-03-30 15:40     ` Thomas Monjalon
2018-03-30 15:57       ` Thomas Monjalon
2018-03-31  0:46     ` Thomas Monjalon
2018-03-21 14:27   ` [dpdk-dev] [PATCH v2 2/4] net/e1000: add TxRx tuning parameters Remy Horton
2018-03-21 14:27   ` [dpdk-dev] [PATCH v2 3/4] net/i40e: " Remy Horton
2018-03-21 14:27   ` [dpdk-dev] [PATCH v2 4/4] testpmd: make use of per-PMD TxRx parameters Remy Horton
2018-03-28  7:18     ` Shreyansh Jain
2018-04-03 11:00       ` Remy Horton
2018-03-31  0:01     ` Thomas Monjalon
2018-04-03  8:49       ` Remy Horton
2018-03-27 18:43   ` [dpdk-dev] [PATCH v2 0/4] ethdev: add per-PMD tuning of RxTx parmeters Ferruh Yigit
2018-03-30 10:34     ` Ferruh Yigit
2018-03-31  0:05       ` Thomas Monjalon
2018-04-04 17:17   ` [dpdk-dev] [PATCH v3 " Remy Horton
2018-04-04 17:17     ` [dpdk-dev] [PATCH v3 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters Remy Horton
2018-04-04 18:56       ` De Lara Guarch, Pablo
2018-04-05 10:16         ` Thomas Monjalon
2018-04-04 17:17     ` [dpdk-dev] [PATCH v3 2/4] net/e1000: add TxRx tuning parameters Remy Horton
2018-04-04 17:17     ` [dpdk-dev] [PATCH v3 3/4] net/i40e: " Remy Horton
2018-04-04 17:17     ` [dpdk-dev] [PATCH v3 4/4] testpmd: make use of per-PMD TxRx parameters Remy Horton
2018-04-06 14:49     ` [dpdk-dev] [PATCH v5 0/4] ethdev: add per-PMD tuning of RxTx parmeters Remy Horton
2018-04-06 14:49       ` [dpdk-dev] [PATCH v5 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters Remy Horton
2018-04-06 14:50       ` [dpdk-dev] [PATCH v5 2/4] net/e1000: add TxRx tuning parameters Remy Horton
2018-04-06 14:50       ` [dpdk-dev] [PATCH v5 3/4] net/i40e: " Remy Horton
2018-04-06 14:50       ` [dpdk-dev] [PATCH v5 4/4] testpmd: make use of per-PMD TxRx parameters Remy Horton
2018-04-09 12:55         ` Shreyansh Jain
2018-04-09 14:38           ` Remy Horton
2018-04-10  4:18             ` Shreyansh Jain
2018-04-10  6:09               ` Remy Horton
2018-04-10  6:39                 ` Shreyansh Jain
2018-04-06 17:01       ` [dpdk-dev] [PATCH v5 0/4] ethdev: add per-PMD tuning of RxTx parmeters Ferruh Yigit
2018-04-10  9:43       ` [dpdk-dev] [PATCH v6 " Remy Horton
2018-04-10  9:43         ` [dpdk-dev] [PATCH v6 1/4] ethdev: add support for PMD-tuned Tx/Rx parameters Remy Horton
2018-04-10  9:43         ` [dpdk-dev] [PATCH v6 2/4] net/e1000: add TxRx tuning parameters Remy Horton
2018-04-10  9:43         ` [dpdk-dev] [PATCH v6 3/4] net/i40e: " Remy Horton
2018-04-10  9:43         ` [dpdk-dev] [PATCH v6 4/4] testpmd: make use of per-PMD TxRx parameters Remy Horton
2018-04-10 12:57         ` [dpdk-dev] [PATCH v6 0/4] ethdev: add per-PMD tuning of RxTx parmeters Thomas Monjalon
2018-04-10 18:56         ` Ferruh Yigit

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