HMM Gets New Features/Improvements, Nouveau Support Aligned For Linux 5.1

Written by Michael Larabel in Linux Kernel on 30 January 2019 at 05:49 AM EST. 3 Comments
Jerome Glisse of Red Hat has spent the past few years devoted to Heterogeneous Memory Management (HMM) that continues stepping towards taking on bigger roles within the Linux kernel. With the upcoming Linux 5.1 kernel cycle there are slated to be more additions to this code, which is the backbone of allowing the mirroring of process address spaces, system memory to be transparently used by any device process, and other functionality for GPU computing and other modern PCIe devices.

The latest HMM additions are supporting hugetlbfs (huge pages) and DAX mirroring (mirror a file on a DAX-backed file-system) along with some API improvements. This latest work is part of a broader effort for adding RDMA ODP (On-Demand Paging) support to Heterogeneous Memory Management. However, that the ODP HMM support isn't expected to be merged until the Linux 5.2~5.3 kernel.

Also exciting about the Linux 5.1 plans is that Jerome will try to merge the Nouveau HMM patches for the open-source NVIDIA driver. HMM patches for Nouveau have been around for a while as one of the early open-source users to this code but come the next kernel cycle the work should be merged. The Nouveau work includes shared virtual memory (SVM) and a new ioctl to allow migrating process memory to GPU memory.

Jerome also commented that he intends to use this latest HMM state as the basis for his latest AMD Radeon and Intel driver patches.

The latest HMM Linux kernel patches can be found on the mailing list.
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