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From: Christoph Hellwig <hch@lst.de>
To: Felix Kuehling <felix.kuehling@amd.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
	Felix Kuehling <felix.kuehling@gmail.com>,
	dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
	jglisse@redhat.com, amd-gfx@lists.freedesktop.org,
	akpm@linux-foundation.org, hch@lst.de
Subject: Re: [RFC PATCH 0/5] Support DEVICE_GENERIC memory in migrate_vma_*
Date: Sat, 29 May 2021 08:41:24 +0200	[thread overview]
Message-ID: <20210529064124.GC15834@lst.de> (raw)
In-Reply-To: <f0bb142b-ab80-c16e-77dd-c7e1aa88c755@amd.com>

On Fri, May 28, 2021 at 11:56:36AM -0400, Felix Kuehling wrote:
> Am 2021-05-28 um 9:08 a.m. schrieb Jason Gunthorpe:
> > 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?
> 
> Yes. For a typical GPU compute application it means the GPU gets the
> best bandwidth/latency, and the CPU can coherently access the results
> without page faults and migrations. That's especially valuable for
> applications with persistent compute kernels that want to exploit
> concurrency between CPU and GPU.

So why not expose the GPU memory as a CPUless memory node?


  reply	other threads:[~2021-05-29  6:41 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 ` [RFC PATCH 0/5] Support DEVICE_GENERIC memory in migrate_vma_* Jason Gunthorpe
2021-05-28 15:56   ` Felix Kuehling
2021-05-29  6:41     ` Christoph Hellwig [this message]
2021-05-29 18:37       ` Felix Kuehling

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