On Thu, Apr 11, 2019 at 12:29:43PM +0000, Leon Romanovsky wrote: > On Wed, Apr 10, 2019 at 11:41:24AM -0400, jglisse@xxxxxxxxxx wrote: > > From: Jérôme Glisse <jglisse@xxxxxxxxxx> > > > > Changes since v1/v2 are about rebase and better comments in the code. > > Previous cover letter slightly updated. > > > > > > This patchset convert RDMA ODP to use HMM underneath this is motivated > > by stronger code sharing for same feature (share virtual memory SVM or > > Share Virtual Address SVA) and also stronger integration with mm code to > > achieve that. It depends on HMM patchset posted for inclusion in 5.2 [2] > > and [3]. > > > > It has been tested with pingpong test with -o and others flags to test > > different size/features associated with ODP. > > > > Moreover they are some features of HMM in the works like peer to peer > > support, fast CPU page table snapshot, fast IOMMU mapping update ... > > It will be easier for RDMA devices with ODP to leverage those if they > > use HMM underneath. > > > > Quick summary of what HMM is: > > HMM is a toolbox for device driver to implement software support for > > Share Virtual Memory (SVM). Not only it provides helpers to mirror a > > process address space on a device (hmm_mirror). It also provides > > helper to allow to use device memory to back regular valid virtual > > address of a process (any valid mmap that is not an mmap of a device > > or a DAX mapping). They are two kinds of device memory. Private memory > > that is not accessible to CPU because it does not have all the expected > > properties (this is for all PCIE devices) or public memory which can > > also be access by CPU without restriction (with OpenCAPI or CCIX or > > similar cache-coherent and atomic inter-connect). > > > > Device driver can use each of HMM tools separatly. You do not have to > > use all the tools it provides. > > > > For RDMA device i do not expect a need to use the device memory support > > of HMM. This device memory support is geared toward accelerator like GPU. > > > > > > You can find a branch [1] with all the prerequisite in. This patch is on > > top of rdma-next with the HMM patchset [2] and mmu notifier patchset [3] > > applied on top of it. > > > > [1] https://cgit.freedesktop.org/~glisse/linux/log/?h=rdma-5.2 > > Hi Jerome, > > I took this branch and merged with our latest rdma-next, but it doesn't > compile. > > In file included from drivers/infiniband/hw/mlx5/mem.c:35: > ./include/rdma/ib_umem_odp.h:110:20: error: field _mirror_ has > incomplete type > struct hmm_mirror mirror; > ^~~~~~ > ./include/rdma/ib_umem_odp.h:132:18: warning: _struct hmm_range_ declared inside parameter list will not be visible outside of this definition or declaration > struct hmm_range *range); > ^~~~~~~~~ > make[4]: *** [scripts/Makefile.build:276: drivers/infiniband/hw/mlx5/mem.o] Error 1 > > The reason to it that in my .config, ZONE_DEVICE, MEMORY_HOTPLUG and HMM options were disabled. Silly my i forgot to update kconfig so i pushed a branch with proper kconfig changes in the ODP patch but it depends on changes to the HMM kconfig so that HMM_MIRROR can be enabled on arch that do not have everything for HMM_DEVICE. https://cgit.freedesktop.org/~glisse/linux/log/?h=rdma-odp-hmm-v4 I doing build of various kconfig variation before posting to make sure it is all good. Cheers, Jérôme
