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: Fri, 16 Mar 2018 19:24:14 +0530 [thread overview]
Message-ID: <CAJ5mUsXFZcsA3PZTSv+Eu+Pt2bKrhMezG-akynaLpJCMFpgCGQ@mail.gmail.com> (raw)
In-Reply-To: <97dc9f9d-041b-ef99-2ca6-1f557c4f6039@intel.com>
On Thu, Mar 15, 2018 at 8:27 PM, Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> On 3/15/2018 2:39 PM, Bruce Richardson wrote:
>> On Thu, Mar 15, 2018 at 01:57:13PM +0000, Ferruh Yigit wrote:
>>> On 3/14/2018 9:36 PM, Bruce Richardson wrote:
>>>> On Wed, Mar 14, 2018 at 09:02:47PM +0000, Ferruh Yigit wrote:
>>>>> On 3/14/2018 6:53 PM, Ananyev, Konstantin wrote:
>>>>>>
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
>>>>>>> Sent: Wednesday, March 14, 2018 5:52 PM
>>>>>>> To: Shreyansh Jain <shreyansh.jain@nxp.com>; Horton, Remy <remy.horton@intel.com>; dev@dpdk.org
>>>>>>> Cc: 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
>>>>>>>
>>>>>>> On 3/14/2018 5:23 PM, Shreyansh Jain wrote:
>>>>>>>>> -----Original Message-----
>>>>>>>>> From: Ferruh Yigit [mailto:ferruh.yigit@intel.com]
>>>>>>>>> Sent: Wednesday, March 14, 2018 10:13 PM
>>>>>>>>> To: Remy Horton <remy.horton@intel.com>; dev@dpdk.org
>>>>>>>>> Cc: Wenzhuo Lu <wenzhuo.lu@intel.com>; Jingjing Wu
>>>>>>>>> <jingjing.wu@intel.com>; Qi Zhang <qi.z.zhang@intel.com>; Beilei Xing
>>>>>>>>> <beilei.xing@intel.com>; Shreyansh Jain <shreyansh.jain@nxp.com>;
>>>>>>>>> Thomas Monjalon <thomas@monjalon.net>
>>>>>>>>> Subject: Re: [dpdk-dev] [RFC PATCH v1 1/4] ethdev: add support for PMD-
>>>>>>>>> tuned Tx/Rx parameters
>>>>>>>>>
>>>>>>>>> On 3/14/2018 3:48 PM, Remy Horton wrote:
>>>>>>>>>>
>>>>>>>>>> On 14/03/2018 14:43, Ferruh Yigit wrote:
>>>>>>>>>> [..]
>>>>>>>>>>>> lib/librte_ether/rte_ethdev.c | 18 ++++++++++++++++++
>>>>>>>>>>>> lib/librte_ether/rte_ethdev.h | 15 +++++++++++++++
>>>>>>>>>>>
>>>>>>>>>>> Can you please remove deprecation notice in this patch.
>>>>>>>>>>
>>>>>>>>>> Done.
>>>>>>>>>>
>>>>>>>>>>>> + /* Defaults for drivers that don't implement preferred
>>>>>>>>>>>> + * queue parameters.
>>>>>>>>>> [..]
>>>>>>>>>>> Not sure about having these defaults here. It is OK to have defaults
>>>>>>>>> in driver,
>>>>>>>>>>> in application or in config file, but I am not sure if putting them
>>>>>>>>> into device
>>>>>>>>>>> abstraction layer hides them.
>>>>>>>>>>>
>>>>>>>>>>> What about not providing any default in ethdev layer, and get zero
>>>>>>>>> as invalid
>>>>>>>>>>> when using them?
>>>>>>>>>>
>>>>>>>>>> This is something I have been thinking about, and I am going to
>>>>>>>>> remove
>>>>>>>>>> them for the V2. Original motive was to avoid breaking testpmd for
>>>>>>>>> PMDs
>>>>>>>>>> that don't give defaults (i.e. almost all of them). The alternative
>>>>>>>>> is
>>>>>>>>>> to put place-holders into all the PMDs themselves, but I am not sure
>>>>>>>>> if
>>>>>>>>>> this is appropriate.
>>>>>>>>>
>>>>>>>>> I think preferred values should be optional, PMD should have right to
>>>>>>>>> not
>>>>>>>>> provide any. Implementation in 4/4 forces preferred values, either in
>>>>>>>>> all PMDs
>>>>>>>>> or in ethdev layer.
>>>>>>>>>
>>>>>>>>> What about changing approach in application:
>>>>>>>>> is preferred value provided [1] ?
>>>>>>>>> yes => use it by sending value 0
>>>>>>>>> no => use application provided value, same as now, so control should
>>>>>>>>> be in
>>>>>>>>> application.
>>>>>>>>>
>>>>>>>>> I am aware this breaks the comfort of just providing 0 and PMD values
>>>>>>>>> will be
>>>>>>>>> used but covers the case there is no PMD values.
>>>>>>>>>
>>>>>>>>> [1]
>>>>>>>>> it can be possible to check if preferred value provided by comparing 0,
>>>>>>>>> but if 0
>>>>>>>>> is a valid value that can be problem. It may not be problem with
>>>>>>>>> current
>>>>>>>>> variables but it may be when this struct extended, it may be good to
>>>>>>>>> think about
>>>>>>>>> alternative here.
>>>>>>>>
>>>>>>>> I don't think we should use the condition of "yes => use it by sending value 0". That is non-intuitive. Ideally, the application should query
>>>>>>> and then if query responds with value as '0' (which can be valid for some variables in future), it sends its own value to setup functions
>>>>>>> (whether '0' or something else, in case of 0 response, would depend on the knob).
>>>>>>>
>>>>>>> Right, at that stage application already knows what is the preferred value and
>>>>>>> can directly use it.
>>>>>>>
>>>>>>>
>>>>>>> Will it be too much to:
>>>>>>>
>>>>>>> 1) Adding a new field into "rte_eth_[rt]xconf" to say if exists prefer PMD
>>>>>>> values. "prefer_device_values" ?
>>>>>>> Application can provide values as usual, but if that field is set, abstraction
>>>>>>> layer overwrites the application values with PMD preferred ones. If there is no
>>>>>>> PMD preferred values continue using application ones.
>>>>>>>
>>>>>>>
>>>>>>> 2) Add a bitwise "is_set" field to new "preferred_size" struct, which may show
>>>>>>> status of other fields in the struct, if PMD set a valid value for them or not,
>>>>>>> so won't have to rely on the 0 check.
>>>>>>
>>>>>> That all seems like too much hassle for such small thing.
>>>>>
>>>>> Fair enough.
>>>>>
>>>>>> If we really want to allow PMD not to provide preferred values -
>>>>>> then instead of adding rte_eth_dev_pref_info into dev_info we can simply
>>>>>> introduce a new optional ethdev API call:
>>>>>> rte_eth_get_pref_params() or so.
>>>>>> If the PMD doesn’t want to provide preferred params to the user it simply
>>>>>> wouldn't implement that function.
>>>>>
>>>>> Same can be done with updated rte_eth_dev_info.
>>>>> Only application needs to check and use PMD preferred values, so this will mean
>>>>> dropping "pass 0 to get preferred values" feature in initial set.
>>>>>
>>>>>>
>>>> I actually don't see the issue with having ethdev provide reasonable
>>>> default values. If those don't work for a driver, then let the driver
>>>> provide it's own values. If the defaults don't work for an app, then let
>>>> the app override the provided values.
>>>>
>>>> It really is going to make the app writers job easier if we do things this
>>>> way. The only thing you are missing is the info as to whether it's ethdev
>>>> or the driver that's providing the values, but in the case that it's
>>>> ethdev, then the driver by definition "doesn't care", so we can treat them
>>>> as driver provided values. What's the downside?
>>> Abstraction layer having hardcoded config options doesn't look right to me. In
>>> long term who will ensure to make those values relevant?
>>>
>>
>> Let me turn that question around - in the long-term how likely are the
>> values to change significantly? Also, long-term all PMDs should provide
>> their own default values and then we can remove the values in the ethdev
>> layer.
>>
>>> When application provides a value of 0, it won't know if it is using PMD
>>> preferred values or some other defaults, what if application explicitly wants
>>> use PMD preferred values?
>>
>> If the PMD has preferred values, they will be automatically used. Is there
>> are case where the app would actually care about it? If the driver doesn't
>> provide default values, how is the app supposed to know what the correct
>> value for that driver is? And if the app *does* know what the best value
>> for a driver is - even if the driver itself doesn't, it can easily detect
>> when a port is using the driver and provide it's own ring setup defaults.
>> If you want, we can provide a flag field to indicate that fields are ethdev
>> defaults not driver defaults or something, but I'm struggling to come up
>> with a scenario where it would make a practical difference to an app.
>>
>>>
>>> The new fields are very similar to "default_[rt]xconf" in dev_info. Indeed
>>> perhaps we should use same naming convention because intention seems same.
>>> And we can continue to use new fields same as how "default_[rt]xconf" used.
>>>
>>> What about having something like rte_eth_tx_queue_setup_relaxed() where
>>> application really don't care about values, not sure why, which can get config
>>> values as much as from PMDs and fill the missing ones with the values defined in
>>> function?
>>>
>>
>> Or how about having the ethdev defaults in the rx/tx setup function instead
>> of in the dev_info one? If user specifies a zero size, we use the dev_info
>> value if provided by driver, otherwise ethdev default. That allows the
>> majority of apps to never worry about ring sizes, but for those that do,
>> they can query the driver defaults directly, or if not present set their
>> own.
>
> OK this at least gives a way to application to know where defaults are coming from.
>
>
> 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.
: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.
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.
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.
D) Would there be no non-Rx and non-Tx defaults which need to be shared?
I am not sure about this, though.
Sorry if I am repeating everything again, but I got lost in the
conversation and needed to break it again.
next prev parent reply other threads:[~2018-03-16 13:54 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 [this message]
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
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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