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From: Christoph Hellwig <hch@infradead.org>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Christoph Hellwig <hch@infradead.org>,
	Yonatan Maman <ymaman@nvidia.com>,
	nouveau@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-rdma@vger.kernel.org, linux-mm@kvack.org,
	herbst@redhat.com, lyude@redhat.com, dakr@redhat.com,
	airlied@gmail.com, simona@ffwll.ch, leon@kernel.org,
	jglisse@redhat.com, akpm@linux-foundation.org,
	dri-devel@lists.freedesktop.org, apopple@nvidia.com,
	bskeggs@nvidia.com, Gal Shalom <GalShalom@nvidia.com>
Subject: Re: [PATCH v1 1/4] mm/hmm: HMM API for P2P DMA to device zone pages
Date: Thu, 17 Oct 2024 06:49:30 -0700	[thread overview]
Message-ID: <ZxEV6ocpKLjPC8H4@infradead.org> (raw)
In-Reply-To: <20241017134644.GA948948@ziepe.ca>

On Thu, Oct 17, 2024 at 10:46:44AM -0300, Jason Gunthorpe wrote:
> On Thu, Oct 17, 2024 at 06:12:55AM -0700, Christoph Hellwig wrote:
> > On Thu, Oct 17, 2024 at 10:05:39AM -0300, Jason Gunthorpe wrote:
> > > Broadly I think whatever flow NVMe uses for P2P will apply to ODP as
> > > well.
> > 
> > ODP is a lot simpler than NVMe for P2P actually :(
> 
> What is your thinking there? I'm looking at the latest patches and I
> would expect dma_iova_init() to accept a phys so it can call
> pci_p2pdma_map_type() once for the whole transaction. It is a slow
> operation.

You can't do it for the whole transaction.  Here is my suggestion
for ODP:

http://git.infradead.org/?p=users/hch/misc.git;a=shortlog;h=refs/heads/dma-split-wip

For NVMe I need to figure out a way to split bios on a per P2P
type boundary as we don't have any space to record if something is a bus
mapped address.



  reply	other threads:[~2024-10-17 13:49 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-15 15:23 [PATCH v1 0/4] GPU Direct RDMA (P2P DMA) for Device Private Pages Yonatan Maman
2024-10-15 15:23 ` [PATCH v1 1/4] mm/hmm: HMM API for P2P DMA to device zone pages Yonatan Maman
2024-10-16  4:49   ` Christoph Hellwig
2024-10-16 15:04     ` Yonatan Maman
2024-10-16 15:44     ` Jason Gunthorpe
2024-10-16 16:41       ` Christoph Hellwig
2024-10-16 17:44         ` Jason Gunthorpe
2024-10-17 11:58           ` Christoph Hellwig
2024-10-17 13:05             ` Jason Gunthorpe
2024-10-17 13:12               ` Christoph Hellwig
2024-10-17 13:46                 ` Jason Gunthorpe
2024-10-17 13:49                   ` Christoph Hellwig [this message]
2024-10-17 14:05                     ` Jason Gunthorpe
2024-10-17 14:19                       ` Christoph Hellwig
2024-10-16  5:10   ` Alistair Popple
2024-10-16 15:45     ` Jason Gunthorpe
2024-10-17  1:58       ` Alistair Popple
2024-10-17 11:53         ` Jason Gunthorpe
2024-10-15 15:23 ` [PATCH v1 2/4] nouveau/dmem: HMM P2P DMA for private dev pages Yonatan Maman
2024-10-16  5:12   ` Alistair Popple
2024-10-16 15:18     ` Yonatan Maman
2024-10-15 15:23 ` [PATCH v1 3/4] IB/core: P2P DMA for device private pages Yonatan Maman
2024-10-15 15:23 ` [PATCH v1 4/4] RDMA/mlx5: Enabling ATS for ODP memory Yonatan Maman
2024-10-16  4:23 ` [PATCH v1 0/4] GPU Direct RDMA (P2P DMA) for Device Private Pages Christoph Hellwig
2024-10-16 15:16   ` Yonatan Maman
2024-10-16 22:22     ` Alistair Popple
2024-10-18  7:26     ` Zhu Yanjun
2024-10-20 15:26       ` Yonatan Maman

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