John Hubbard <jhubbard@xxxxxxxxxx> writes: > On Fri, 18 Nov 2016, Jérôme Glisse wrote: > >> Cliff note: HMM offers 2 things (each standing on its own). First >> it allows to use device memory transparently inside any process >> without any modifications to process program code. Second it allows >> to mirror process address space on a device. >> >> Change since v12 is the use of struct page for device memory even if >> the device memory is not accessible by the CPU (because of limitation >> impose by the bus between the CPU and the device). >> >> Using struct page means that their are minimal changes to core mm >> code. HMM build on top of ZONE_DEVICE to provide struct page, it >> adds new features to ZONE_DEVICE. The first 7 patches implement >> those changes. >> >> Rest of patchset is divided into 3 features that can each be use >> independently from one another. First is the process address space >> mirroring (patch 9 to 13), this allow to snapshot CPU page table >> and to keep the device page table synchronize with the CPU one. >> >> Second is a new memory migration helper which allow migration of >> a range of virtual address of a process. This memory migration >> also allow device to use their own DMA engine to perform the copy >> between the source memory and destination memory. This can be >> usefull even outside HMM context in many usecase. >> >> Third part of the patchset (patch 17-18) is a set of helper to >> register a ZONE_DEVICE node and manage it. It is meant as a >> convenient helper so that device drivers do not each have to >> reimplement over and over the same boiler plate code. >> >> >> I am hoping that this can now be consider for inclusion upstream. >> Bottom line is that without HMM we can not support some of the new >> hardware features on x86 PCIE. I do believe we need some solution >> to support those features or we won't be able to use such hardware >> in standard like C++17, OpenCL 3.0 and others. >> >> I have been working with NVidia to bring up this feature on their >> Pascal GPU. There are real hardware that you can buy today that >> could benefit from HMM. We also intend to leverage this inside the >> open source nouveau driver. >> > > Hi, > > We (NVIDIA engineering) have been working closely with Jerome on this for > several years now, and I wanted to mention that NVIDIA is committed to > using HMM. We've done initial testing of this patchset on Pascal GPUs (a > bit more detail below) and it is looking good. > This can also be used on IBM platforms like Minsky ( http://www.tomshardware.com/news/ibm-power8-nvidia-tesla-p100-minsky,32661.html ) There is also discussion around using this for device accelerated page migration. That can help with coherent device memory node work. (https://lkml.kernel.org/r/1477283517-2504-1-git-send-email-khandual@xxxxxxxxxxxxxxxxxx) -aneesh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href