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From: Jason Gunthorpe <>
To: Felix Kuehling <>
Subject: Re: [RFC PATCH 0/5] Support DEVICE_GENERIC memory in migrate_vma_*
Date: Fri, 28 May 2021 10:08:16 -0300	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, May 27, 2021 at 07:08:04PM -0400, Felix Kuehling wrote:
> Now we're trying to migrate data to and from that memory using the
> migrate_vma_* helpers so we can support page-based migration in our
> unified memory allocations, while also supporting CPU access to those
> pages.

So you have completely coherent and indistinguishable GPU and CPU
memory and the need of migration is basicaly alot like NUMA policy
choice - get better access locality?
> This patch series makes a few changes to make MEMORY_DEVICE_GENERIC pages
> behave correctly in the migrate_vma_* helpers. We are looking for feedback
> about this approach. If we're close, what's needed to make our patches
> acceptable upstream? If we're not close, any suggestions how else to
> achieve what we are trying to do (i.e. page migration and coherent CPU
> access to VRAM)?

I'm not an expert in migrate, but it doesn't look outrageous.

Have you thought about allowing MEMORY_DEVICE_GENERIC to work with
hmm_range_fault() so you can have nice uniform RDMA?

People have wanted to do that with MEMORY_DEVICE_PRIVATE but nobody
finished the work


  parent reply	other threads:[~2021-05-28 13:08 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-27 23:08 Felix Kuehling
2021-05-27 23:08 ` [RFC PATCH 1/5] drm/amdkfd: add SPM support for SVM Felix Kuehling
2021-05-29  6:38   ` Christoph Hellwig
2021-05-29 18:42     ` Felix Kuehling
2021-05-27 23:08 ` [RFC PATCH 2/5] drm/amdkfd: generic type as sys mem on migration to ram Felix Kuehling
2021-05-27 23:08 ` [RFC PATCH 3/5] include/linux/mm.h: helper to check zone device generic type Felix Kuehling
2021-05-27 23:08 ` [RFC PATCH 4/5] mm: add generic type support for device zone page migration Felix Kuehling
2021-05-29  6:40   ` Christoph Hellwig
2021-05-27 23:08 ` [RFC PATCH 5/5] mm: changes to unref pages with Generic type Felix Kuehling
2021-05-29  6:42   ` Christoph Hellwig
2021-05-29 18:44     ` Felix Kuehling
2021-05-28 13:08 ` Jason Gunthorpe [this message]
2021-05-28 15:56   ` [RFC PATCH 0/5] Support DEVICE_GENERIC memory in migrate_vma_* Felix Kuehling
2021-05-29  6:41     ` Christoph Hellwig
2021-05-29 18:37       ` Felix Kuehling

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