From: Jason Gunthorpe <jgg@ziepe.ca> To: Christoph Hellwig <hch@infradead.org> Cc: "Christian König" <christian.koenig@amd.com>, David1.Zhou@amd.com, daniel@ffwll.ch, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org, "Logan Gunthorpe" <logang@deltatee.com> Subject: Re: [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function Date: Fri, 13 Mar 2020 09:17:42 -0300 [thread overview] Message-ID: <20200313121742.GZ31668@ziepe.ca> (raw) In-Reply-To: <20200313112139.GA4913@infradead.org> On Fri, Mar 13, 2020 at 04:21:39AM -0700, Christoph Hellwig wrote: > On Thu, Mar 12, 2020 at 11:19:28AM -0300, Jason Gunthorpe wrote: > > The non-page scatterlist is also a big concern for RDMA as we have > > drivers that want the page list, so even if we did as this series > > contemplates I'd have still have to split the drivers and create the > > notion of a dma-only SGL. > > The drivers I looked at want a list of IOVA address, aligned to the > device "page size". What other data do drivers want? Execept for the > software protocol stack drivers, which of couse need pages for the > stack futher down. In principle it is possible to have just an aligned page list - however the page size is variable, following certain rules, and today the drivers still determine the correct page size largely on their own. Some progress was made recently to consolidate this, but more is needed. If the common code doesn't know the device page size in advance then today's approach of sending largest possible dma mapped SGLs into the device driver is best. The driver only has to do splitting. > > I haven't used bio_vecs before, do they support chaining like SGL so > > they can be very big? RDMA dma maps gigabytes of memory > > bio_vecs itself don't have the chaining, but the bios build around them > do. But each entry can map a huge pile. If needed we could use the > same chaining scheme we use for scatterlists for bio_vecs as well, but > lets see if we really end up needing that. RDMA surely needs something to generate huge lists of dma mapped memory. MRs are very big objects Jason
WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@ziepe.ca> To: Christoph Hellwig <hch@infradead.org> Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, "Logan Gunthorpe" <logang@deltatee.com>, "Christian König" <christian.koenig@amd.com>, linux-media@vger.kernel.org Subject: Re: [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function Date: Fri, 13 Mar 2020 09:17:42 -0300 [thread overview] Message-ID: <20200313121742.GZ31668@ziepe.ca> (raw) In-Reply-To: <20200313112139.GA4913@infradead.org> On Fri, Mar 13, 2020 at 04:21:39AM -0700, Christoph Hellwig wrote: > On Thu, Mar 12, 2020 at 11:19:28AM -0300, Jason Gunthorpe wrote: > > The non-page scatterlist is also a big concern for RDMA as we have > > drivers that want the page list, so even if we did as this series > > contemplates I'd have still have to split the drivers and create the > > notion of a dma-only SGL. > > The drivers I looked at want a list of IOVA address, aligned to the > device "page size". What other data do drivers want? Execept for the > software protocol stack drivers, which of couse need pages for the > stack futher down. In principle it is possible to have just an aligned page list - however the page size is variable, following certain rules, and today the drivers still determine the correct page size largely on their own. Some progress was made recently to consolidate this, but more is needed. If the common code doesn't know the device page size in advance then today's approach of sending largest possible dma mapped SGLs into the device driver is best. The driver only has to do splitting. > > I haven't used bio_vecs before, do they support chaining like SGL so > > they can be very big? RDMA dma maps gigabytes of memory > > bio_vecs itself don't have the chaining, but the bios build around them > do. But each entry can map a huge pile. If needed we could use the > same chaining scheme we use for scatterlists for bio_vecs as well, but > lets see if we really end up needing that. RDMA surely needs something to generate huge lists of dma mapped memory. MRs are very big objects Jason _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2020-03-13 12:17 UTC|newest] Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-11 13:51 P2P for DMA-buf Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 13:51 ` [PATCH 1/6] lib/scatterlist: add sg_set_dma_addr() function Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 15:28 ` Christoph Hellwig 2020-03-11 15:28 ` [Intel-gfx] " Christoph Hellwig 2020-03-12 10:14 ` Christian König 2020-03-12 10:14 ` [Intel-gfx] " Christian König 2020-03-12 10:14 ` Christian König 2020-03-12 10:19 ` Christoph Hellwig 2020-03-12 10:19 ` [Intel-gfx] " Christoph Hellwig 2020-03-12 10:31 ` Christian König 2020-03-12 10:31 ` [Intel-gfx] " Christian König 2020-03-12 10:31 ` Christian König 2020-03-12 10:47 ` Christoph Hellwig 2020-03-12 10:47 ` [Intel-gfx] " Christoph Hellwig 2020-03-12 11:02 ` Christian König 2020-03-12 11:02 ` [Intel-gfx] " Christian König 2020-03-12 11:02 ` Christian König 2020-03-12 14:19 ` Jason Gunthorpe 2020-03-12 14:19 ` Jason Gunthorpe 2020-03-12 15:39 ` Christian König 2020-03-12 15:39 ` [Intel-gfx] " Christian König 2020-03-12 15:39 ` Christian König 2020-03-12 16:19 ` Jason Gunthorpe 2020-03-12 16:19 ` Jason Gunthorpe 2020-03-12 16:13 ` Logan Gunthorpe 2020-03-12 16:13 ` [Intel-gfx] " Logan Gunthorpe 2020-03-12 16:13 ` Logan Gunthorpe 2020-03-13 11:21 ` Christoph Hellwig 2020-03-13 11:21 ` [Intel-gfx] " Christoph Hellwig 2020-03-13 12:17 ` Jason Gunthorpe [this message] 2020-03-13 12:17 ` Jason Gunthorpe 2020-03-16 8:56 ` Christoph Hellwig 2020-03-16 8:56 ` [Intel-gfx] " Christoph Hellwig 2020-03-16 9:41 ` Christian König 2020-03-16 9:41 ` [Intel-gfx] " Christian König 2020-03-16 9:41 ` Christian König 2020-03-16 9:52 ` Christoph Hellwig 2020-03-16 9:52 ` [Intel-gfx] " Christoph Hellwig 2020-03-16 12:37 ` Jason Gunthorpe 2020-03-16 12:37 ` Jason Gunthorpe 2020-03-13 13:33 ` Christian König 2020-03-13 13:33 ` [Intel-gfx] " Christian König 2020-03-13 13:33 ` Christian König 2020-03-11 13:51 ` [PATCH 2/6] dma-buf: add peer2peer flag Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 13:51 ` [PATCH 3/6] drm/amdgpu: note that we can handle peer2peer DMA-buf Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 13:51 ` [PATCH 4/6] drm/amdgpu: add checks if DMA-buf P2P is supported Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 14:04 ` Jason Gunthorpe 2020-03-11 14:04 ` Jason Gunthorpe 2020-03-11 14:33 ` Christian König 2020-03-11 14:33 ` [Intel-gfx] " Christian König 2020-03-11 14:33 ` Christian König 2020-03-11 14:38 ` Jason Gunthorpe 2020-03-11 14:38 ` Jason Gunthorpe 2020-03-11 14:43 ` Christian König 2020-03-11 14:43 ` [Intel-gfx] " Christian König 2020-03-11 14:43 ` Christian König 2020-03-11 14:48 ` Jason Gunthorpe 2020-03-11 14:48 ` Jason Gunthorpe 2020-03-11 13:51 ` [PATCH 5/6] drm/amdgpu: add support for exporting VRAM using DMA-buf v2 Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 14:33 ` Jason Gunthorpe 2020-03-11 14:33 ` Jason Gunthorpe 2020-03-11 14:39 ` Jason Gunthorpe 2020-03-11 14:39 ` Jason Gunthorpe 2020-03-11 15:08 ` Alex Deucher 2020-03-11 15:08 ` [Intel-gfx] " Alex Deucher 2020-03-11 15:08 ` Alex Deucher 2020-03-11 13:51 ` [PATCH 6/6] drm/amdgpu: improve amdgpu_gem_info debugfs file Christian König 2020-03-11 13:51 ` [Intel-gfx] " Christian König 2020-03-11 13:51 ` Christian König 2020-03-11 18:09 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/6] lib/scatterlist: add sg_set_dma_addr() function Patchwork 2020-03-11 18:34 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
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