DPDK patches and discussions
 help / color / mirror / Atom feed
From: "Pai G, Sunil" <sunil.pai.g@intel.com>
To: Jerin Jacob <jerinjacobk@gmail.com>
Cc: "Hu, Jiayu" <jiayu.hu@intel.com>,
	"Richardson, Bruce" <bruce.richardson@intel.com>,
	dpdk-dev <dev@dpdk.org>, "Walsh, Conor" <conor.walsh@intel.com>,
	"Laatz, Kevin" <kevin.laatz@intel.com>,
	fengchengwen <fengchengwen@huawei.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: Tue, 21 Sep 2021 15:34:59 +0000	[thread overview]
Message-ID: <BYAPR11MB38144064CA32E6781461B527BDA19@BYAPR11MB3814.namprd11.prod.outlook.com> (raw)
In-Reply-To: <CALBAE1M_hNksUZHYgRSvORr_w=YoxVd4QF3UhT5YxUBzU0QtUA@mail.gmail.com>

Hi Jerin,

<snipped>

> > > > The fact is  that it's very hard for apps to calculate the
> > > > available space of a
> > > DMA ring.
> > >
> > > Yes, I agree.
> > >
> > > My question is more why to calculate the space per burst and
> > > introduce yet another fastpath API.
> > > For example, the application needs to copy 8 segments to complete a
> > > logical copy in the application perspective.
> > > In case, when 8th copy is completed then only the application marks
> > > the logical copy completed.
> > > i.e why to check per burst, 8 segments are available or not? Even it
> > > is available, there may be multiple reasons why any of the segment
> > > copies can fail. So the application needs to track all the jobs completed or
> not anyway.
> > > Am I missing something in terms of vhost or OVS usage?
> > >
> >
> > For the packets that do not entirely fit in the DMA ring , we have a SW copy
> fallback in place.
> > So, we would like to avoid scenario caused because of DMA ring full where
> few parts of the packet are copied through DMA and other parts by CPU.
> > Besides, this API would also help improve debuggability/device
> introspection to check the occupancy rather than the app having to manually
> track the state of every DMA device in use.
> 
> 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/20210907120021.4093604-2-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.

<snipped>

Thanks and regards,
Sunil


  reply	other threads:[~2021-09-21 15:35 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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=BYAPR11MB38144064CA32E6781461B527BDA19@BYAPR11MB3814.namprd11.prod.outlook.com \
    --to=sunil.pai.g@intel.com \
    --cc=bruce.richardson@intel.com \
    --cc=conor.walsh@intel.com \
    --cc=dev@dpdk.org \
    --cc=fengchengwen@huawei.com \
    --cc=jerinj@marvell.com \
    --cc=jerinjacobk@gmail.com \
    --cc=jiayu.hu@intel.com \
    --cc=kevin.laatz@intel.com \
    --cc=radhac@marvell.com \
    --cc=sburla@marvell.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).