From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Shahaf Shuler <shahafs@mellanox.com>,
Alejandro Lucero <alejandro.lucero@netronome.com>
Cc: Yongseok Koh <yskoh@mellanox.com>,
Thomas Monjalon <thomas@monjalon.net>,
Ferruh Yigit <ferruh.yigit@intel.com>,
"nhorman@tuxdriver.com" <nhorman@tuxdriver.com>,
Gaetan Rivet <gaetan.rivet@6wind.com>, dev <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 0/6] introduce DMA memory mapping for external memory
Date: Thu, 14 Feb 2019 10:19:03 +0000 [thread overview]
Message-ID: <81f4bbef-8d6a-d845-eb07-966bbccf4849@intel.com> (raw)
In-Reply-To: <AM0PR0502MB3795448496DA4721C809ECE6C3660@AM0PR0502MB3795.eurprd05.prod.outlook.com>
On 13-Feb-19 7:24 PM, Shahaf Shuler wrote:
> Wednesday, February 13, 2019 1:43 PM, Alejandro Lucero:
>> Subject: Re: [dpdk-dev] [PATCH 0/6] introduce DMA memory mapping for
>> external memory
>>
>> On Wed, Feb 13, 2019 at 9:11 AM Shahaf Shuler <shahafs@mellanox.com>
>> wrote:
>>
>>> This series is in continue to RFC[1].
>>>
>>> The DPDK APIs expose 3 different modes to work with memory used for
>> DMA:
>>>
>>> 1. Use the DPDK owned memory (backed by the DPDK provided
>> hugepages).
>>> This memory is allocated by the DPDK libraries, included in the DPDK
>>> memory system (memseg lists) and automatically DMA mapped by the
>> DPDK
>>> layers.
>>>
>>> 2. Use memory allocated by the user and register to the DPDK memory
>>> systems. This is also referred as external memory. Upon registration
>>> of the external memory, the DPDK layers will DMA map it to all needed
>>> devices.
>>>
>>> 3. Use memory allocated by the user and not registered to the DPDK
>>> memory system. This is for users who wants to have tight control on
>>> this memory. The user will need to explicitly call DMA map function in
>>> order to register such memory to the different devices.
>>>
>>> The scope of the patch focus on #3 above.
>>>
>>>
>> Why can not we have case 2 covering case 3?
>
> Because it is not our choice rather the DPDK application.
> We could not allow it, and force the application to register their external memory to the DPDK memory management system. However IMO it will be wrong.
> The use case exists - some application wants to manage their memory by themselves. w/o the extra overhead of rte_malloc, without creating a special socket to populate the memory and without redundant API calls to rte_extmem_*.
>
> Simply allocate chunk of memory, DMA map it to device and that’s it.
Just a small note: while this sounds good on paper, i should point out
that at least *registering* the memory with DPDK is a necessity. You may
see rte_extmem_* calls as redundant (and i agree, to an extent), but we
don't advertise our PMD's capabilities in a way that makes it easy to
determine whether a particular PMD will or will not work without
registering external memory within DPDK (i.e. does it use
rte_virt2memseg() internally, for example).
So, extmem register calls are a necessary evil in such case, and IMO
should be called out as required for such external memory usage scenario.
--
Thanks,
Anatoly
next prev parent reply other threads:[~2019-02-14 10:19 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 9:10 Shahaf Shuler
2019-02-13 9:10 ` [dpdk-dev] [PATCH 1/6] vfio: allow DMA map of memory for the default vfio fd Shahaf Shuler
2019-02-13 9:45 ` Gaëtan Rivet
2019-02-13 11:38 ` Gaëtan Rivet
2019-02-13 15:23 ` Shahaf Shuler
2019-02-13 14:41 ` Burakov, Anatoly
2019-02-13 9:10 ` [dpdk-dev] [PATCH 2/6] vfio: don't fail to DMA map if memory is already mapped Shahaf Shuler
2019-02-13 9:58 ` Gaëtan Rivet
2019-02-13 19:52 ` Shahaf Shuler
2019-02-13 9:10 ` [dpdk-dev] [PATCH 3/6] bus: introduce DMA memory mapping for external memory Shahaf Shuler
2019-02-13 11:17 ` Gaëtan Rivet
2019-02-13 19:07 ` Shahaf Shuler
2019-02-14 14:00 ` Gaëtan Rivet
2019-02-17 6:23 ` Shahaf Shuler
2019-02-13 9:10 ` [dpdk-dev] [PATCH 4/6] net/mlx5: refactor external memory registration Shahaf Shuler
2019-02-13 9:10 ` [dpdk-dev] [PATCH 5/6] net/mlx5: support PCI device DMA map and unmap Shahaf Shuler
2019-02-13 11:35 ` Gaëtan Rivet
2019-02-13 11:44 ` Gaëtan Rivet
2019-02-13 19:11 ` Shahaf Shuler
2019-02-14 10:21 ` Gaëtan Rivet
2019-02-21 9:21 ` Shahaf Shuler
2019-02-13 9:10 ` [dpdk-dev] [PATCH 6/6] doc: deprecate VFIO DMA map APIs Shahaf Shuler
2019-02-13 11:43 ` [dpdk-dev] [PATCH 0/6] introduce DMA memory mapping for external memory Alejandro Lucero
2019-02-13 19:24 ` Shahaf Shuler
2019-02-14 10:19 ` Burakov, Anatoly [this message]
2019-02-14 13:28 ` Shahaf Shuler
2019-02-14 16:19 ` Burakov, Anatoly
2019-02-17 6:18 ` Shahaf Shuler
2019-02-18 12:21 ` Burakov, Anatoly
2019-02-14 12:22 ` Alejandro Lucero
2019-02-14 12:27 ` Alejandro Lucero
2019-02-14 13:41 ` Shahaf Shuler
2019-02-14 16:43 ` Burakov, Anatoly
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 " Shahaf Shuler
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 " Shahaf Shuler
2019-03-10 8:27 ` [dpdk-dev] [PATCH v4 " Shahaf Shuler
2019-03-10 8:27 ` [dpdk-dev] [PATCH v4 1/6] vfio: allow DMA map of memory for the default vfio fd Shahaf Shuler
2019-03-30 0:23 ` Thomas Monjalon
2019-03-30 0:23 ` Thomas Monjalon
2019-03-30 14:29 ` Thomas Monjalon
2019-03-30 14:29 ` Thomas Monjalon
2019-03-10 8:27 ` [dpdk-dev] [PATCH v4 2/6] vfio: don't fail to DMA map if memory is already mapped Shahaf Shuler
2019-03-10 8:28 ` [dpdk-dev] [PATCH v4 3/6] bus: introduce device level DMA memory mapping Shahaf Shuler
2019-03-11 10:19 ` Burakov, Anatoly
2019-03-13 9:56 ` Thomas Monjalon
2019-03-13 11:12 ` Shahaf Shuler
2019-03-13 11:19 ` Thomas Monjalon
2019-03-13 11:47 ` Burakov, Anatoly
2019-03-30 14:36 ` Thomas Monjalon
2019-03-30 14:36 ` Thomas Monjalon
2019-03-10 8:28 ` [dpdk-dev] [PATCH v4 4/6] net/mlx5: refactor external memory registration Shahaf Shuler
2019-03-10 8:28 ` [dpdk-dev] [PATCH v4 5/6] net/mlx5: support PCI device DMA map and unmap Shahaf Shuler
2019-03-10 8:28 ` [dpdk-dev] [PATCH v4 6/6] doc: deprecation notice for VFIO DMA map APIs Shahaf Shuler
2019-03-11 10:20 ` Burakov, Anatoly
2019-03-11 17:35 ` Rami Rosen
2019-10-01 15:20 ` David Marchand
2019-10-02 4:53 ` Shahaf Shuler
2019-10-02 7:51 ` David Marchand
2019-03-11 9:27 ` [dpdk-dev] [PATCH v4 0/6] introduce DMA memory mapping for external memory Gaëtan Rivet
2019-03-30 14:40 ` Thomas Monjalon
2019-03-30 14:40 ` Thomas Monjalon
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 1/6] vfio: allow DMA map of memory for the default vfio fd Shahaf Shuler
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 2/6] vfio: don't fail to DMA map if memory is already mapped Shahaf Shuler
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 3/6] bus: introduce device level DMA memory mapping Shahaf Shuler
2019-03-05 16:35 ` Burakov, Anatoly
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 4/6] net/mlx5: refactor external memory registration Shahaf Shuler
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 5/6] net/mlx5: support PCI device DMA map and unmap Shahaf Shuler
2019-03-05 13:59 ` [dpdk-dev] [PATCH v3 6/6] doc: deprecation notice for VFIO DMA map APIs Shahaf Shuler
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 1/6] vfio: allow DMA map of memory for the default vfio fd Shahaf Shuler
2019-02-28 11:56 ` Burakov, Anatoly
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 2/6] vfio: don't fail to DMA map if memory is already mapped Shahaf Shuler
2019-02-28 11:58 ` Burakov, Anatoly
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 3/6] bus: introduce device level DMA memory mapping Shahaf Shuler
2019-02-28 12:14 ` Burakov, Anatoly
2019-02-28 14:41 ` Burakov, Anatoly
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 4/6] net/mlx5: refactor external memory registration Shahaf Shuler
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 5/6] net/mlx5: support PCI device DMA map and unmap Shahaf Shuler
2019-02-21 14:50 ` [dpdk-dev] [PATCH v2 6/6] doc: deprecate VFIO DMA map APIs Shahaf Shuler
2019-02-21 15:50 ` David Marchand
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