Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded Gabbay wrote:
Another thing I want to emphasize is that we are doing p2p only
through the export/import of the FD. We do *not* allow the user to
mmap the dma-buf as we do not support direct IO. So there
On Tue, Jun 22, 2021 at 9:37 AM Christian König
wrote:
>
> Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
> > On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded Gabbay wrote:
> >
> >> Another thing I want to emphasize is that we are doing p2p only
> >> through the export/import of the FD. We do *not* a
On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> On Tue, Jun 22, 2021 at 9:37 AM Christian König
> wrote:
> >
> > Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
> > > On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded Gabbay wrote:
> > >
> > >> Another thing I want to emphasize is that we
On Tue, Jun 22, 2021 at 3:01 PM Jason Gunthorpe wrote:
>
> On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> > On Tue, Jun 22, 2021 at 9:37 AM Christian König
> > wrote:
> > >
> > > Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
> > > > On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded G
On Tue, Jun 22, 2021 at 03:04:30PM +0300, Oded Gabbay wrote:
> On Tue, Jun 22, 2021 at 3:01 PM Jason Gunthorpe wrote:
> >
> > On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> > > On Tue, Jun 22, 2021 at 9:37 AM Christian König
> > > wrote:
> > > >
> > > > Am 22.06.21 um 01:29 schrie
Am 22.06.21 um 14:01 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
On Tue, Jun 22, 2021 at 9:37 AM Christian König
wrote:
Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
On Mon, Jun 21, 2021 at 10:24:16PM +0300, Oded Gabbay wrote:
Another thing I want t
On Tue, Jun 22, 2021 at 3:15 PM Jason Gunthorpe wrote:
>
> On Tue, Jun 22, 2021 at 03:04:30PM +0300, Oded Gabbay wrote:
> > On Tue, Jun 22, 2021 at 3:01 PM Jason Gunthorpe wrote:
> > >
> > > On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> > > > On Tue, Jun 22, 2021 at 9:37 AM Chris
On Tue, Jun 22, 2021 at 04:12:26PM +0300, Oded Gabbay wrote:
> > 1) Setting sg_page to NULL
> > 2) 'mapping' pages for P2P DMA without going through the iommu
> > 3) Allowing P2P DMA without using the p2p dma API to validate that it
> >can work at all in the first place.
> >
> > All of these r
On Tue, Jun 22, 2021 at 02:23:03PM +0200, Christian König wrote:
> Am 22.06.21 um 14:01 schrieb Jason Gunthorpe:
> > On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> > > On Tue, Jun 22, 2021 at 9:37 AM Christian König
> > > wrote:
> > > > Am 22.06.21 um 01:29 schrieb Jason Gunthorpe:
Am 22.06.21 um 17:11 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 04:12:26PM +0300, Oded Gabbay wrote:
1) Setting sg_page to NULL
2) 'mapping' pages for P2P DMA without going through the iommu
3) Allowing P2P DMA without using the p2p dma API to validate that it
can work at all in th
On Tue, Jun 22, 2021 at 6:11 PM Jason Gunthorpe wrote:
>
> On Tue, Jun 22, 2021 at 04:12:26PM +0300, Oded Gabbay wrote:
>
> > > 1) Setting sg_page to NULL
> > > 2) 'mapping' pages for P2P DMA without going through the iommu
> > > 3) Allowing P2P DMA without using the p2p dma API to validate that i
On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
> > > I will take two GAUDI devices and use one as an exporter and one as an
> > > importer. I want to see that the solution works end-to-end, with real
> > > device DMA from importer to exporter.
> > I can tell you it doesn't. Stuff
Am 22.06.21 um 17:23 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 02:23:03PM +0200, Christian König wrote:
Am 22.06.21 um 14:01 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
On Tue, Jun 22, 2021 at 9:37 AM Christian König
wrote:
Am 22.06.21 um 01:2
Am 22.06.21 um 17:28 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
I will take two GAUDI devices and use one as an exporter and one as an
importer. I want to see that the solution works end-to-end, with real
device DMA from importer to exporter.
I
On Tue, Jun 22, 2021 at 6:28 PM Jason Gunthorpe wrote:
>
> On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
>
> > > > I will take two GAUDI devices and use one as an exporter and one as an
> > > > importer. I want to see that the solution works end-to-end, with real
> > > > device
On Tue, Jun 22, 2021 at 06:24:28PM +0300, Oded Gabbay wrote:
> On Tue, Jun 22, 2021 at 6:11 PM Jason Gunthorpe wrote:
> >
> > On Tue, Jun 22, 2021 at 04:12:26PM +0300, Oded Gabbay wrote:
> >
> > > > 1) Setting sg_page to NULL
> > > > 2) 'mapping' pages for P2P DMA without going through the iommu
>
On Tue, Jun 22, 2021 at 05:29:01PM +0200, Christian König wrote:
> Am 22.06.21 um 17:23 schrieb Jason Gunthorpe:
> > On Tue, Jun 22, 2021 at 02:23:03PM +0200, Christian König wrote:
> > > Am 22.06.21 um 14:01 schrieb Jason Gunthorpe:
> > > > On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wro
On Tue, Jun 22, 2021 at 6:31 PM Christian König
wrote:
>
>
>
> Am 22.06.21 um 17:28 schrieb Jason Gunthorpe:
> > On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
> >
> I will take two GAUDI devices and use one as an exporter and one as an
> importer. I want to see that th
Am 22.06.21 um 17:40 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 05:29:01PM +0200, Christian König wrote:
[SNIP]
No absolutely not. NVidia GPUs work exactly the same way.
And you have tons of similar cases in embedded and SoC systems where
intermediate memory between devices isn't directly
Am 22.06.21 um 17:40 schrieb Oded Gabbay:
On Tue, Jun 22, 2021 at 6:31 PM Christian König
wrote:
Am 22.06.21 um 17:28 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 05:24:08PM +0200, Christian König wrote:
I will take two GAUDI devices and use one as an exporter and one as an
importer. I
On Tue, Jun 22, 2021 at 05:48:10PM +0200, Christian König wrote:
> Am 22.06.21 um 17:40 schrieb Jason Gunthorpe:
> > On Tue, Jun 22, 2021 at 05:29:01PM +0200, Christian König wrote:
> > > [SNIP]
> > > No absolutely not. NVidia GPUs work exactly the same way.
> > >
> > > And you have tons of simila
Am 2021-06-22 um 11:29 a.m. schrieb Christian König:
> Am 22.06.21 um 17:23 schrieb Jason Gunthorpe:
>> On Tue, Jun 22, 2021 at 02:23:03PM +0200, Christian König wrote:
>>> Am 22.06.21 um 14:01 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 11:42:27AM +0300, Oded Gabbay wrote:
> On Tue,
Am 22.06.21 um 18:05 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 05:48:10PM +0200, Christian König wrote:
Am 22.06.21 um 17:40 schrieb Jason Gunthorpe:
On Tue, Jun 22, 2021 at 05:29:01PM +0200, Christian König wrote:
[SNIP]
No absolutely not. NVidia GPUs work exactly the same way.
And yo
On Wed, Jun 23, 2021 at 11:57 AM Christian König
wrote:
>
> Am 22.06.21 um 18:05 schrieb Jason Gunthorpe:
> > On Tue, Jun 22, 2021 at 05:48:10PM +0200, Christian König wrote:
> >> Am 22.06.21 um 17:40 schrieb Jason Gunthorpe:
> >>> On Tue, Jun 22, 2021 at 05:29:01PM +0200, Christian König wrote:
>
On Wed, Jun 23, 2021 at 10:57:35AM +0200, Christian König wrote:
> > > No it isn't. It makes devices depend on allocating struct pages for their
> > > BARs which is not necessary nor desired.
> > Which dramatically reduces the cost of establishing DMA mappings, a
> > loop of dma_map_resource() is
On Wed, Jun 23, 2021 at 9:24 PM Jason Gunthorpe wrote:
>
> On Wed, Jun 23, 2021 at 10:57:35AM +0200, Christian König wrote:
>
> > > > No it isn't. It makes devices depend on allocating struct pages for
> > > > their
> > > > BARs which is not necessary nor desired.
> > > Which dramatically reduces
On Wed, Jun 23, 2021 at 09:43:04PM +0300, Oded Gabbay wrote:
> Can you please explain why it is so important to (allow) access them
> through the CPU ?
It is not so much important, as it reflects significant design choices
that are already tightly baked into alot of our stacks.
A SGL is CPU acc
On Wed, Jun 23, 2021 at 9:50 PM Jason Gunthorpe wrote:
>
> On Wed, Jun 23, 2021 at 09:43:04PM +0300, Oded Gabbay wrote:
>
> > Can you please explain why it is so important to (allow) access them
> > through the CPU ?
>
> It is not so much important, as it reflects significant design choices
> that
On Wed, Jun 23, 2021 at 10:00:29PM +0300, Oded Gabbay wrote:
> On Wed, Jun 23, 2021 at 9:50 PM Jason Gunthorpe wrote:
> >
> > On Wed, Jun 23, 2021 at 09:43:04PM +0300, Oded Gabbay wrote:
> >
> > > Can you please explain why it is so important to (allow) access them
> > > through the CPU ?
> >
> >
On Wed, Jun 23, 2021 at 10:34 PM Jason Gunthorpe wrote:
>
> On Wed, Jun 23, 2021 at 10:00:29PM +0300, Oded Gabbay wrote:
> > On Wed, Jun 23, 2021 at 9:50 PM Jason Gunthorpe wrote:
> > >
> > > On Wed, Jun 23, 2021 at 09:43:04PM +0300, Oded Gabbay wrote:
> > >
> > > > Can you please explain why it
On Wed, Jun 23, 2021 at 10:39:48PM +0300, Oded Gabbay wrote:
> On Wed, Jun 23, 2021 at 10:34 PM Jason Gunthorpe wrote:
> >
> > On Wed, Jun 23, 2021 at 10:00:29PM +0300, Oded Gabbay wrote:
> > > On Wed, Jun 23, 2021 at 9:50 PM Jason Gunthorpe wrote:
> > > >
> > > > On Wed, Jun 23, 2021 at 09:43:04
Am 24.06.21 um 07:34 schrieb Christoph Hellwig:
On Wed, Jun 23, 2021 at 10:00:29PM +0300, Oded Gabbay wrote:
I understand the argument and I agree that for the generic case, the
top of the stack can't assume anything.
Having said that, in this case the SGL is encapsulated inside a dma-buf object
Am 24.06.21 um 10:12 schrieb Christoph Hellwig:
On Thu, Jun 24, 2021 at 10:07:14AM +0200, Christian König wrote:
The key point is that accessing the underlying pages even when DMA-bufs are
backed by system memory is illegal. Daniel even created a patch which
mangles the page pointers in sg_table
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