On Mon, 24 Apr 2023 17:28:01 +0200, Alexander Lobakin <aleksander.lobakin@xxxxxxxxx> wrote: > From: Jakub Kicinski <kuba@xxxxxxxxxx> > Date: Fri, 21 Apr 2023 06:50:59 -0700 > > > On Fri, 21 Apr 2023 15:31:04 +0800 Xuan Zhuo wrote: > >> I am not particularly familiar with dma-bufs. I want to know if this mechanism > >> can solve the problem of virtio-net. > >> > >> I saw this framework, allowing the driver do something inside the ops of > >> dma-bufs. > >> > >> If so, is it possible to propose a new patch based on dma-bufs? > > > > I haven't looked in detail, maybe Olek has? AFAIU you'd need to rework > > Oh no, not me. I suck at dma-bufs, tried to understand them several > times with no progress :D My knowledge is limited to "ok, if it's > DMA + userspace, then it's likely dma-buf" :smile_with_tear: > > > uAPI of XSK to allow user to pass in a dma-buf region rather than just > > a user VA. So it may be a larger effort but architecturally it may be > > the right solution. > > > > I'm curious whether this could be done without tons of work. Switching > Page Pool to dma_alloc_noncoherent() is simpler :D But, as I wrote > above, we need to extend DMA API first to provide bulk allocations and > NUMA-aware allocations. > Can't we provide a shim for back-compat, i.e. if a program passes just a > user VA, create a dma-buf in the kernel already? Yes I think so too. If this is the case, will the workload be much smaller? Let me try it. Thanks. > > Thanks, > Olek
