From: "Christian König" <christian.koenig@amd.com>
To: Dave Airlie <airlied@gmail.com>, Alex Deucher <alexdeucher@gmail.com>
Cc: Danilo Krummrich <dakr@redhat.com>,
tzimmermann@suse.de, corbet@lwn.net,
nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
bskeggs@redhat.com, jason@jlekstrand.net, airlied@redhat.com
Subject: Re: [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI
Date: Wed, 18 Jan 2023 20:48:48 +0100 [thread overview]
Message-ID: <7839c47e-6692-b93b-69a8-9584193cb07d@amd.com> (raw)
In-Reply-To: <CAPM=9txMZO1uYj+kVdTfmCwV2Fq8uu_b3i4eq4xhqPEPKBW8Eg@mail.gmail.com>
Am 18.01.23 um 20:17 schrieb Dave Airlie:
> On Thu, 19 Jan 2023 at 02:54, Alex Deucher <alexdeucher@gmail.com> wrote:
>> On Wed, Jan 18, 2023 at 11:50 AM Danilo Krummrich <dakr@redhat.com> wrote:
>>>
>>>
>>> On 1/18/23 17:30, Alex Deucher wrote:
>>>> On Wed, Jan 18, 2023 at 11:19 AM Danilo Krummrich <dakr@redhat.com> wrote:
>>>>> On 1/18/23 16:37, Christian König wrote:
>>>>>> Am 18.01.23 um 16:34 schrieb Danilo Krummrich:
>>>>>>> Hi Christian,
>>>>>>>
>>>>>>> On 1/18/23 09:53, Christian König wrote:
>>>>>>>> Am 18.01.23 um 07:12 schrieb Danilo Krummrich:
>>>>>>>>> This patch series provides a new UAPI for the Nouveau driver in
>>>>>>>>> order to
>>>>>>>>> support Vulkan features, such as sparse bindings and sparse residency.
>>>>>>>>>
>>>>>>>>> Furthermore, with the DRM GPUVA manager it provides a new DRM core
>>>>>>>>> feature to
>>>>>>>>> keep track of GPU virtual address (VA) mappings in a more generic way.
>>>>>>>>>
>>>>>>>>> The DRM GPUVA manager is indented to help drivers implement
>>>>>>>>> userspace-manageable
>>>>>>>>> GPU VA spaces in reference to the Vulkan API. In order to achieve
>>>>>>>>> this goal it
>>>>>>>>> serves the following purposes in this context.
>>>>>>>>>
>>>>>>>>> 1) Provide a dedicated range allocator to track GPU VA
>>>>>>>>> allocations and
>>>>>>>>> mappings, making use of the drm_mm range allocator.
>>>>>>>> This means that the ranges are allocated by the kernel? If yes that's
>>>>>>>> a really really bad idea.
>>>>>>> No, it's just for keeping track of the ranges userspace has allocated.
>>>>>> Ok, that makes more sense.
>>>>>>
>>>>>> So basically you have an IOCTL which asks kernel for a free range? Or
>>>>>> what exactly is the drm_mm used for here?
>>>>> Not even that, userspace provides both the base address and the range,
>>>>> the kernel really just keeps track of things. Though, writing a UAPI on
>>>>> top of the GPUVA manager asking for a free range instead would be
>>>>> possible by just adding the corresponding wrapper functions to get a
>>>>> free hole.
>>>>>
>>>>> Currently, and that's what I think I read out of your question, the main
>>>>> benefit of using drm_mm over simply stuffing the entries into a list or
>>>>> something boils down to easier collision detection and iterating
>>>>> sub-ranges of the whole VA space.
>>>> Why not just do this in userspace? We have a range manager in
>>>> libdrm_amdgpu that you could lift out into libdrm or some other
>>>> helper.
>>> The kernel still needs to keep track of the mappings within the various
>>> VA spaces, e.g. it silently needs to unmap mappings that are backed by
>>> BOs that get evicted and remap them once they're validated (or swapped
>>> back in).
>> Ok, you are just using this for maintaining the GPU VM space in the kernel.
>>
> Yes the idea behind having common code wrapping drm_mm for this is to
> allow us to make the rules consistent across drivers.
>
> Userspace (generally Vulkan, some compute) has interfaces that pretty
> much dictate a lot of how VMA tracking works, esp around lifetimes,
> sparse mappings and splitting/merging underlying page tables, I'd
> really like this to be more consistent across drivers, because already
> I think we've seen with freedreno some divergence from amdgpu and we
> also have i915/xe to deal with. I'd like to at least have one place
> that we can say this is how it should work, since this is something
> that *should* be consistent across drivers mostly, as it is more about
> how the uapi is exposed.
That's a really good idea, but the implementation with drm_mm won't work
like that.
We have Vulkan applications which use the sparse feature to create
literally millions of mappings. That's why I have fine tuned the mapping
structure in amdgpu down to ~80 bytes IIRC and save every CPU cycle
possible in the handling of that.
A drm_mm_node is more in the range of ~200 bytes and certainly not
suitable for this kind of job.
I strongly suggest to rather use a good bunch of the amdgpu VM code as
blueprint for the common infrastructure.
Regards,
Christian.
>
> Dave.
next prev parent reply other threads:[~2023-01-18 19:49 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-18 6:12 [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 01/14] drm: execution context for GEM buffers Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 02/14] drm/exec: fix memory leak in drm_exec_prepare_obj() Danilo Krummrich
2023-01-18 8:51 ` Christian König
2023-01-18 19:00 ` Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 03/14] drm: manager to keep track of GPUs VA mappings Danilo Krummrich
2023-01-19 4:14 ` Bagas Sanjaya
2023-01-20 18:32 ` Danilo Krummrich
2023-01-23 23:23 ` Niranjana Vishwanathapura
2023-01-26 23:43 ` Matthew Brost
2023-01-27 0:24 ` Matthew Brost
2023-02-03 17:37 ` Matthew Brost
2023-02-06 13:35 ` Christian König
2023-02-06 13:46 ` Danilo Krummrich
2023-02-14 11:52 ` Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 04/14] drm: debugfs: provide infrastructure to dump a DRM GPU VA space Danilo Krummrich
2023-01-18 13:55 ` kernel test robot
2023-01-18 15:47 ` kernel test robot
2023-01-18 6:12 ` [PATCH drm-next 05/14] drm/nouveau: new VM_BIND uapi interfaces Danilo Krummrich
2023-01-27 1:05 ` Matthew Brost
2023-01-27 1:26 ` Danilo Krummrich
2023-01-27 7:55 ` Christian König
2023-01-27 13:12 ` Danilo Krummrich
2023-01-27 13:23 ` Christian König
2023-01-27 14:44 ` Danilo Krummrich
2023-01-27 15:17 ` Christian König
2023-01-27 20:25 ` David Airlie
2023-01-30 12:58 ` Christian König
2023-01-27 21:09 ` Danilo Krummrich
2023-01-29 18:46 ` Danilo Krummrich
2023-01-30 13:02 ` Christian König
2023-01-30 23:38 ` Danilo Krummrich
2023-02-01 8:10 ` [Nouveau] " Dave Airlie
2023-02-02 11:53 ` Christian König
2023-02-02 18:31 ` Danilo Krummrich
2023-02-06 9:48 ` Christian König
2023-02-06 13:27 ` Danilo Krummrich
2023-02-06 16:14 ` Christian König
2023-02-06 18:20 ` Danilo Krummrich
2023-02-07 9:35 ` Christian König
2023-02-07 10:50 ` Danilo Krummrich
2023-02-10 11:50 ` Christian König
2023-02-10 12:47 ` Danilo Krummrich
2023-01-27 1:43 ` Danilo Krummrich
2023-01-27 3:21 ` Matthew Brost
2023-01-27 3:33 ` Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 06/14] drm/nouveau: get vmm via nouveau_cli_vmm() Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 07/14] drm/nouveau: bo: initialize GEM GPU VA interface Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 08/14] drm/nouveau: move usercopy helpers to nouveau_drv.h Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 09/14] drm/nouveau: fence: fail to emit when fence context is killed Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 10/14] drm/nouveau: chan: provide nouveau_channel_kill() Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 11/14] drm/nouveau: nvkm/vmm: implement raw ops to manage uvmm Danilo Krummrich
2023-01-20 3:37 ` kernel test robot
2023-01-18 6:12 ` [PATCH drm-next 12/14] drm/nouveau: implement uvmm for user mode bindings Danilo Krummrich
2023-01-18 6:12 ` [PATCH drm-next 13/14] drm/nouveau: implement new VM_BIND UAPI Danilo Krummrich
2023-01-18 20:37 ` Thomas Hellström (Intel)
2023-01-19 3:44 ` Danilo Krummrich
2023-01-19 4:58 ` Matthew Brost
2023-01-19 7:32 ` Thomas Hellström (Intel)
2023-01-20 10:08 ` Boris Brezillon
2023-01-18 6:12 ` [PATCH drm-next 14/14] drm/nouveau: debugfs: implement DRM GPU VA debugfs Danilo Krummrich
2023-01-18 8:53 ` [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI Christian König
2023-01-18 15:34 ` Danilo Krummrich
2023-01-18 15:37 ` Christian König
2023-01-18 16:19 ` Danilo Krummrich
2023-01-18 16:30 ` Alex Deucher
2023-01-18 16:50 ` Danilo Krummrich
2023-01-18 16:54 ` Alex Deucher
2023-01-18 19:17 ` Dave Airlie
2023-01-18 19:48 ` Christian König [this message]
2023-01-19 4:04 ` Danilo Krummrich
2023-01-19 5:23 ` Matthew Brost
2023-01-19 11:33 ` drm_gpuva_manager requirements (was Re: [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI) Christian König
2023-02-06 14:48 ` [PATCH drm-next 00/14] [RFC] DRM GPUVA Manager & Nouveau VM_BIND UAPI Oded Gabbay
2023-03-16 16:39 ` Danilo Krummrich
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