From: Logan Gunthorpe <logang@deltatee.com>
To: "Christian König" <christian.koenig@amd.com>,
"Christoph Hellwig" <hch@infradead.org>
Cc: linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org,
dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/8] PCI: Add pci_find_common_upstream_dev()
Date: Wed, 28 Mar 2018 10:25:43 -0600 [thread overview]
Message-ID: <16c7bef8-5f03-9e89-1f50-b62fb139a36f@deltatee.com> (raw)
In-Reply-To: <5498e9b5-8fe5-8999-a44e-f7dc483bc9ce@amd.com>
On 28/03/18 10:02 AM, Christian König wrote:
> Yeah, that looks very similar to what I picked up from the older
> patches, going to read up on that after my vacation.
Yeah, I was just reading through your patchset and there are a lot of
similarities. Though, I'm not sure what you're trying to accomplish as I
could not find a cover letter and it seems to only enable one driver. Is
it meant to enable DMA transactions only between two AMD GPUs?
I also don't see where you've taken into account the PCI bus address. On
some architectures this is not the same as the CPU physical address.
> Just in general why are you interested in the "distance" of the devices?
We've taken a general approach where some drivers may provide p2p memory
(ie. an NVMe card or an RDMA NIC) and other drivers make use of it (ie.
the NVMe-of driver). The orchestrator driver needs to find the most
applicable provider device for a transaction in a situation that may
have multiple providers and multiple clients. So the most applicable
provider is the one that's closest ("distance"-wise) to all the clients
for the P2P transaction.
> And BTW: At least for writes that Peer 2 Peer transactions between
> different root complexes work is actually more common than the other way
> around.
Maybe on x86 with hardware made in the last few years. But on PowerPC,
ARM64, and likely a lot more the chance of support is *much* less. Also,
hardware that only supports P2P stores is hardly full support and is
insufficient for our needs.
> So I'm a bit torn between using a blacklist or a whitelist. A whitelist
> is certainly more conservative approach, but that could get a bit long.
I think a whitelist approach is correct. Given old hardware and other
architectures, a black list is going to be too long and too difficult to
comprehensively populate.
Logan
next prev parent reply other threads:[~2018-03-28 16:25 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-25 10:59 [PATCH 1/8] lib/scatterlist: add sg_set_dma_addr() helper Christian König
2018-03-25 10:59 ` [PATCH 2/8] PCI: Add pci_find_common_upstream_dev() Christian König
2018-03-28 12:38 ` Christoph Hellwig
2018-03-28 15:07 ` Christian König
2018-03-28 15:47 ` Logan Gunthorpe
2018-03-28 16:02 ` Christian König
2018-03-28 16:25 ` Logan Gunthorpe [this message]
2018-03-28 18:28 ` Christian König
2018-03-28 18:57 ` Logan Gunthorpe
2018-03-28 19:44 ` Christian König
2018-03-28 19:53 ` Logan Gunthorpe
2018-03-29 11:44 ` Christian König
2018-03-29 15:45 ` Logan Gunthorpe
2018-03-29 16:10 ` Christian König
2018-03-29 16:25 ` Logan Gunthorpe
2018-03-29 18:15 ` Christian König
2018-03-30 1:58 ` Jerome Glisse
2018-03-30 6:33 ` Christoph Hellwig
2018-03-30 15:25 ` Jerome Glisse
2018-03-30 18:46 ` Logan Gunthorpe
2018-03-30 19:45 ` Jerome Glisse
2018-04-02 17:02 ` Logan Gunthorpe
2018-04-02 17:20 ` Jerome Glisse
2018-04-02 17:37 ` Logan Gunthorpe
2018-04-02 19:16 ` Jerome Glisse
2018-04-02 19:32 ` Logan Gunthorpe
2018-04-02 19:45 ` Jerome Glisse
[not found] ` <CADnq5_P-z=Noos_jaME9_CERri3C-m2hPPvx2bArr36O=1FnrA@mail.gmail.com>
2018-03-29 14:37 ` Alex Deucher
2018-03-25 10:59 ` [PATCH 3/8] PCI: Add pci_peer_traffic_supported() Christian König
2018-03-25 10:59 ` [PATCH 4/8] dma-buf: add peer2peer flag Christian König
2018-03-29 6:57 ` Daniel Vetter
2018-03-29 11:34 ` Christian König
2018-04-03 9:09 ` Daniel Vetter
2018-04-03 17:06 ` Jerome Glisse
2018-04-03 18:08 ` Daniel Vetter
2018-04-16 12:39 ` Christoph Hellwig
2018-04-16 13:38 ` Daniel Vetter
2018-04-19 8:16 ` Christoph Hellwig
2018-04-20 7:13 ` Daniel Vetter
2018-04-20 8:58 ` Christian König
2018-04-20 10:17 ` Christoph Hellwig
2018-04-20 10:44 ` Christian König
2018-04-20 12:46 ` Christoph Hellwig
2018-04-20 15:21 ` [Linaro-mm-sig] " Daniel Vetter
2018-04-24 18:48 ` Christoph Hellwig
2018-04-24 19:32 ` Daniel Vetter
2018-04-25 5:48 ` Christoph Hellwig
2018-04-25 6:10 ` Alex Deucher
2018-04-25 6:13 ` Daniel Vetter
2018-04-25 6:23 ` Daniel Vetter
2018-04-25 6:43 ` Christoph Hellwig
2018-04-25 7:02 ` Daniel Vetter
2018-04-25 7:09 ` Christoph Hellwig
2018-04-25 7:30 ` Daniel Vetter
2018-04-25 7:56 ` Thierry Reding
2018-04-25 8:55 ` Christoph Hellwig
2018-04-25 7:43 ` Thierry Reding
2018-04-25 7:41 ` Thierry Reding
2018-04-25 8:54 ` noveau vs arm dma ops Christoph Hellwig
2018-04-25 9:25 ` Russell King - ARM Linux
2018-04-25 10:04 ` Daniel Vetter
2018-04-25 15:33 ` Christoph Hellwig
2018-04-25 21:35 ` Daniel Vetter
2018-04-25 23:26 ` Russell King - ARM Linux
2018-04-26 9:17 ` Daniel Vetter
2018-04-26 9:09 ` Christoph Hellwig
2018-04-26 9:45 ` Daniel Vetter
2018-04-26 11:12 ` Russell King - ARM Linux
2018-04-25 22:54 ` Russell King - ARM Linux
2018-04-26 9:13 ` Christoph Hellwig
2018-04-26 9:20 ` [Linaro-mm-sig] " Daniel Vetter
2018-04-26 9:24 ` Christoph Hellwig
2018-04-26 9:39 ` Daniel Vetter
2018-04-25 6:24 ` [Linaro-mm-sig] [PATCH 4/8] dma-buf: add peer2peer flag Alex Deucher
2018-04-25 6:41 ` Christoph Hellwig
2018-04-25 17:44 ` Alex Deucher
2018-04-25 18:38 ` Dan Williams
2018-05-04 12:45 ` Lucas Stach
2018-03-25 10:59 ` [PATCH 5/8] drm/amdgpu: print DMA-buf status in debugfs Christian König
2018-03-25 10:59 ` [PATCH 6/8] drm/amdgpu: note that we can handle peer2peer DMA-buf Christian König
2018-03-25 10:59 ` [PATCH 7/8] drm/amdgpu: add amdgpu_gem_attach Christian König
2018-03-25 11:00 ` [PATCH 8/8] drm/amdgpu: add support for exporting VRAM using DMA-buf Christian König
2018-03-28 12:37 ` [PATCH 1/8] lib/scatterlist: add sg_set_dma_addr() helper Christoph Hellwig
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