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From: fengchengwen <fengchengwen@huawei.com>
To: Jerin Jacob <jerinjacobk@gmail.com>,
	Bruce Richardson <bruce.richardson@intel.com>
Cc: "Pai G, Sunil" <sunil.pai.g@intel.com>,
	"Hu, Jiayu" <jiayu.hu@intel.com>,  dpdk-dev <dev@dpdk.org>,
	"Walsh, Conor" <conor.walsh@intel.com>,
	"Laatz, Kevin" <kevin.laatz@intel.com>,
	Jerin Jacob <jerinj@marvell.com>,
	"Satananda Burla" <sburla@marvell.com>,
	Radha Mohan Chintakuntla <radhac@marvell.com>
Subject: Re: [dpdk-dev] [PATCH v3 2/8] dmadev: add burst capacity API
Date: Thu, 23 Sep 2021 21:24:35 +0800	[thread overview]
Message-ID: <8b15cd2b-3a47-b471-3c41-a17c4f0849e3@huawei.com> (raw)
In-Reply-To: <CALBAE1Puqm4gbqXEO_sn+8jR8_fuVrkfaodLmhYEsgj7mhYJwQ@mail.gmail.com>

On 2021/9/23 1:29, Jerin Jacob wrote:
> On Wed, Sep 22, 2021 at 10:06 PM Bruce Richardson
> <bruce.richardson@intel.com> wrote:
>>
>> On Wed, Sep 22, 2021 at 08:56:50AM +0100, Bruce Richardson wrote:
>>> On Wed, Sep 22, 2021 at 09:51:42AM +0800, fengchengwen wrote:
>>>> On 2021/9/22 2:11, Jerin Jacob wrote:
>>>>> On Tue, Sep 21, 2021 at 10:42 PM Pai G, Sunil <sunil.pai.g@intel.com> wrote:
>>>>>>
>>>>>> Hi Jerin,
>>>>>>
>>>>>> <snipped>
>>>>>>
>>>>>>>>> To understand it better, Could you share more details on feedback
>>>>>>>>> mechanism on your application enqueue
>>>>>>>>>
>>>>>>>>> app_enqueue_v1(.., nb_seg)
>>>>>>>>> {
>>>>>>>>>              /* Not enough space, Let application handle it by
>>>>>>>>> dropping or resubmitting */
>>>>>>>>>              if (rte_dmadev_burst_capacity() < nb_seg)
>>>>>>>>>                         return -ENOSPC;
>>>>>>>>>
>>>>>>>>>             do rte_dma_op() in loop without checking error;
>>>>>>>>>             return 0; // Success
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> vs
>>>>>>>>> app_enqueue_v2(.., nb_seg)
>>>>>>>>> {
>>>>>>>>>            int rc;
>>>>>>>>>
>>>>>>>>>             rc |= rte_dma_op() in loop without checking error;
>>>>>>>>>             return rc; // return the actual status to application
>>>>>>>>> if Not enough space, Let application handle it by dropping or
>>>>>>>>> resubmitting */ }
>>>>>>>>>
>>>>>>>>> Is app_enqueue_v1() and app_enqueue_v2() logically the same from
>>>>>>>>> application PoV. Right?
>>>>>>>>>
>>>>>>>>> If not, could you explain, the version you are planning to do for
>>>>>>>>> app_enqueue()
>>>>>>>>
>>>>>>>> The exact version can be found here :
>>>>>>>>
>>>>>>> http://patchwork.ozlabs.org/project/openvswitch/patch/20210907120021.4
>>>>>>>> 093604-2-sunil.pai.g@intel.com/ Unfortunately, both versions are not
>>>>>>>> same in our case because of the SW fallback we have for ring full scenario's.
>>>>>>>> For a packet with 8 nb_segs, if the ring has only space for 4 , we
>>>>>>>> would avoid this packet with app_enqueue_v1 while going ahead with an
>>>>>>> enqueue with app_enqueue_v2, resulting in a mix of DMA and CPU copies
>>>>>>> for a packet which we would want to avoid.
>>>>>>>
>>>>>>> Thanks for RFC link. Usage is clear now, Since you are checking the space in
>>>>>>> the completion handler, I am not sure, what is hard to get the remaining
>>>>>>> space, Will following logic work to find the empty space. If not, please discuss
>>>>>>> the issue with this approach. I am trying to avoid yet another fastpath API
>>>>>>> and complication in driver as there is element checking space in the submit
>>>>>>> queue and completion queue at least in our hardware.
>>>>>>>
>>>>>>>      max_count = nb_desc; (power of 2)
>>>>>>>      mask = max_count - 1;
>>>>>>>
>>>>>>>      for (i = 0; I < n; i++) {
>>>>>>>           submit_idx = rte_dma_copy();
>>>>>>>      }
>>>>>>>      rc = rte_dma_completed(…, &completed_idx..);
>>>>>>>      space_in_queue =  mask - ((submit_idx – completed_idx) & mask);
>>>>>>>
>>>>>>
>>>>>> Unfortunately, space left in the device (as calculated by the app) still can mean there is no space in the device :|
>>>>>> i.e its pmd dependent.
>>>>>
>>>>> I did not pay much attention to Jiayu's reply as I did not know what is DSA.
>>>>> Now I searched the DSA in ml, I could see the PMD patches.
>>>>>
>>>>> If it is PMD limitation then I am fine with the proposed API.
>>>>>
>>>>> @Richardson, Bruce @Laatz, Kevin  @feng Since it is used fastpath, Can
>>>>> we move to fastpath handler and
>>>>> remove additional check in fastpath from common code like other APIs.
>>>>
>>>> +1 for move to fastpath.
>>>>
>>>
>>> Will move in next revision.
>>
>> Follow-up question on this. If it's a fastpath function then we would not
>> normally check for support from drivers. Therefore do we want to:
>> 1. make it a mandatory function
>> 2. add a feature capability flag
>>
>> Given that it's likely fairly easy for all drivers to implement, and it
>> makes it easier for apps to avoid having to check a feature flag for, I'd
>> tend towards option #1, but just would like consensus before I push any
>> more patches.
> 
> I think, if vhost using in that way then it needs to make it a
> mandatory function.

+1

> 
>>
>> /Bruce
> .
> 

  reply	other threads:[~2021-09-23 13:24 UTC|newest]

Thread overview: 130+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-26 18:32 [dpdk-dev] [RFC PATCH 0/7] add test suite for DMA drivers Bruce Richardson
2021-08-26 18:32 ` [dpdk-dev] [RFC PATCH 1/7] app/test: take API tests from skeleton dmadev Bruce Richardson
2021-08-26 18:32 ` [dpdk-dev] [RFC PATCH 2/7] dmadev: remove selftest support Bruce Richardson
2021-08-26 18:32 ` [dpdk-dev] [RFC PATCH 3/7] app/test: add basic dmadev instance tests Bruce Richardson
2021-08-26 18:32 ` [dpdk-dev] [RFC PATCH 4/7] app/test: add basic dmadev copy tests Bruce Richardson
2021-08-27  7:14   ` Jerin Jacob
2021-08-27 10:41     ` Bruce Richardson
2021-08-26 18:32 ` [dpdk-dev] [RFC PATCH 5/7] app/test: add more comprehensive " Bruce Richardson
2021-08-26 18:33 ` [dpdk-dev] [RFC PATCH 6/7] app/test: test dmadev instance failure handling Bruce Richardson
2021-08-26 18:33 ` [dpdk-dev] [RFC PATCH 7/7] app/test: add dmadev fill tests Bruce Richardson
2021-09-01 16:32 ` [dpdk-dev] [PATCH v2 0/6] add test suite for DMA drivers Bruce Richardson
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 1/6] dmadev: add device idle check for testing use Bruce Richardson
2021-09-02 12:54     ` fengchengwen
2021-09-02 14:21       ` Bruce Richardson
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 2/6] app/test: add basic dmadev instance tests Bruce Richardson
2021-09-01 19:24     ` Mattias Rönnblom
2021-09-02 10:30       ` Bruce Richardson
2021-09-03 16:07     ` Conor Walsh
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 3/6] app/test: add basic dmadev copy tests Bruce Richardson
2021-09-02  7:44     ` Jerin Jacob
2021-09-02  8:06       ` Bruce Richardson
2021-09-02 10:54         ` Jerin Jacob
2021-09-02 11:43           ` Bruce Richardson
2021-09-02 13:05             ` Jerin Jacob
2021-09-02 14:21               ` Bruce Richardson
2021-09-03 16:05     ` Kevin Laatz
2021-09-03 16:07     ` Conor Walsh
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 4/6] app/test: add more comprehensive " Bruce Richardson
2021-09-03 16:08     ` Conor Walsh
2021-09-03 16:11     ` Kevin Laatz
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 5/6] app/test: test dmadev instance failure handling Bruce Richardson
2021-09-01 19:53     ` Mattias Rönnblom
2021-09-03 16:08     ` Conor Walsh
2021-09-03 16:21     ` Kevin Laatz
2021-09-01 16:32   ` [dpdk-dev] [PATCH v2 6/6] app/test: add dmadev fill tests Bruce Richardson
2021-09-03 16:09     ` Conor Walsh
2021-09-03 16:17       ` Conor Walsh
2021-09-03 16:33         ` Bruce Richardson
2021-09-07 16:49 ` [dpdk-dev] [PATCH v3 0/8] add test suite for DMA drivers Bruce Richardson
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 1/8] dmadev: add channel status check for testing use Bruce Richardson
2021-09-08 10:50     ` Walsh, Conor
2021-09-08 13:20     ` Kevin Laatz
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 2/8] dmadev: add burst capacity API Bruce Richardson
2021-09-08 10:53     ` Walsh, Conor
2021-09-08 18:17     ` Jerin Jacob
2021-09-09  8:16       ` Bruce Richardson
2021-09-17 13:54         ` Jerin Jacob
2021-09-17 14:37           ` Pai G, Sunil
2021-09-18 12:18             ` Jerin Jacob
2021-09-18  1:06           ` Hu, Jiayu
2021-09-18 12:12             ` Jerin Jacob
2021-09-21 13:57               ` Pai G, Sunil
2021-09-21 14:56                 ` Jerin Jacob
2021-09-21 15:34                   ` Pai G, Sunil
2021-09-21 16:58                     ` Jerin Jacob
2021-09-21 17:12                       ` Pai G, Sunil
2021-09-21 18:11                         ` Jerin Jacob
2021-09-22  1:51                           ` fengchengwen
2021-09-22  7:56                             ` Bruce Richardson
2021-09-22 16:35                               ` Bruce Richardson
2021-09-22 17:29                                 ` Jerin Jacob
2021-09-23 13:24                                   ` fengchengwen [this message]
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 3/8] app/test: add basic dmadev instance tests Bruce Richardson
2021-09-08 13:21     ` Kevin Laatz
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 4/8] app/test: add basic dmadev copy tests Bruce Richardson
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 5/8] app/test: add more comprehensive " Bruce Richardson
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 6/8] app/test: test dmadev instance failure handling Bruce Richardson
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 7/8] app/test: add dmadev fill tests Bruce Richardson
2021-09-07 16:49   ` [dpdk-dev] [PATCH v3 8/8] app/test: add dmadev burst capacity API test Bruce Richardson
2021-09-08 11:03     ` Walsh, Conor
2021-09-17 13:30 ` [dpdk-dev] [PATCH v4 0/9] add test suite for DMA drivers Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 1/9] dmadev: add channel status check for testing use Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 2/9] dmadev: add burst capacity API Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 3/9] dmadev: add device iterator Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 4/9] app/test: add basic dmadev instance tests Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 5/9] app/test: add basic dmadev copy tests Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 6/9] app/test: add more comprehensive " Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 7/9] app/test: test dmadev instance failure handling Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 8/9] app/test: add dmadev fill tests Bruce Richardson
2021-09-17 13:30   ` [dpdk-dev] [PATCH v4 9/9] app/test: add dmadev burst capacity API test Bruce Richardson
2021-09-17 13:54 ` [dpdk-dev] [PATCH v5 0/9] add test suite for DMA drivers Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 1/9] dmadev: add channel status check for testing use Bruce Richardson
2021-09-22  8:25     ` fengchengwen
2021-09-22  8:31       ` Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 2/9] dmadev: add burst capacity API Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 3/9] dmadev: add device iterator Bruce Richardson
2021-09-22  8:46     ` fengchengwen
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 4/9] app/test: add basic dmadev instance tests Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 5/9] app/test: add basic dmadev copy tests Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 6/9] app/test: add more comprehensive " Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 7/9] app/test: test dmadev instance failure handling Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 8/9] app/test: add dmadev fill tests Bruce Richardson
2021-09-17 13:54   ` [dpdk-dev] [PATCH v5 9/9] app/test: add dmadev burst capacity API test Bruce Richardson
2021-09-24 10:29 ` [dpdk-dev] [PATCH v6 00/13] add test suite for DMA drivers Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 01/13] dmadev: add channel status check for testing use Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 02/13] dma/skeleton: add channel status function Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 03/13] dmadev: add burst capacity API Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 04/13] dma/skeleton: add burst capacity function Bruce Richardson
2021-09-24 14:51     ` Conor Walsh
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 05/13] dmadev: add device iterator Bruce Richardson
2021-09-24 14:52     ` Conor Walsh
2021-09-24 15:58     ` Kevin Laatz
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 06/13] app/test: add basic dmadev instance tests Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 07/13] app/test: add basic dmadev copy tests Bruce Richardson
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 08/13] app/test: run test suite on skeleton driver Bruce Richardson
2021-09-24 15:58     ` Kevin Laatz
2021-09-24 10:29   ` [dpdk-dev] [PATCH v6 09/13] app/test: add more comprehensive dmadev copy tests Bruce Richardson
2021-09-24 10:31   ` [dpdk-dev] [PATCH v6 10/13] dmadev: add flag for error handling support Bruce Richardson
2021-09-24 14:52     ` Conor Walsh
2021-09-24 15:58     ` Kevin Laatz
2021-09-24 10:31   ` [dpdk-dev] [PATCH v6 11/13] app/test: test dmadev instance failure handling Bruce Richardson
2021-09-24 10:31   ` [dpdk-dev] [PATCH v6 12/13] app/test: add dmadev fill tests Bruce Richardson
2021-09-24 10:31   ` [dpdk-dev] [PATCH v6 13/13] app/test: add dmadev burst capacity API test Bruce Richardson
2021-10-13 15:17   ` [dpdk-dev] [PATCH v7 00/13] add test suite for DMA drivers Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 01/13] dmadev: add channel status check for testing use Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 02/13] dma/skeleton: add channel status function Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 03/13] dmadev: add burst capacity API Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 04/13] dma/skeleton: add burst capacity function Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 05/13] dmadev: add device iterator Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 06/13] app/test: add basic dmadev instance tests Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 07/13] app/test: add basic dmadev copy tests Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 08/13] app/test: run test suite on skeleton driver Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 09/13] app/test: add more comprehensive dmadev copy tests Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 10/13] dmadev: add flag for error handling support Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 11/13] app/test: test dmadev instance failure handling Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 12/13] app/test: add dmadev fill tests Bruce Richardson
2021-10-13 15:17     ` [dpdk-dev] [PATCH v7 13/13] app/test: add dmadev burst capacity API test Bruce Richardson
2021-10-18  9:20     ` [dpdk-dev] [PATCH v7 00/13] add test suite for DMA drivers Thomas Monjalon
2021-10-21 12:06       ` fengchengwen
2021-10-21 14:55         ` Bruce Richardson

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