Messages in this thread | | | Subject | Re: [Linaro-mm-sig] [PATCH v3 1/2] habanalabs: define uAPI to export FD for DMA-BUF | From | Christian König <> | Date | Tue, 22 Jun 2021 08:37:15 +0200 |
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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 is no access >> to these pages through the userspace. > Arguably mmaping the memory is a better choice, and is the direction > that Logan's series goes in. Here the use of DMABUF was specifically > designed to allow hitless revokation of the memory, which this isn't > even using.
The major problem with this approach is that DMA-buf is also used for memory which isn't CPU accessible.
That was one of the reasons we didn't even considered using the mapping memory approach for GPUs.
Regards, Christian.
> > So you are taking the hit of very limited hardware support and reduced > performance just to squeeze into DMABUF.. > > Jason > _______________________________________________ > Linaro-mm-sig mailing list > Linaro-mm-sig@lists.linaro.org > https://lists.linaro.org/mailman/listinfo/linaro-mm-sig
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