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9fegpNrlXcSc7q/3PvPWnK2IULpznXdJsLcvXNUO6LH7ySOvTOP4EBFWF13MFW3pQHwqzSmeyWxt3cfT+qjh7Ci2dtwTaEw3i6NmxxLBG+z97TBOjMAp++QoNa3Hl0ygwej0Wc63zNh2zSN+Fw0bTz8FR6WMHOAKsKhjuiBfnd4rzvM4gqwElJ4hEJMVoOIuoiWZJqLdCYfpIe3Yczc6mfGvMUqW+n1SmEX74 X-Bogosity: Ham, tests=bogofilter, spamicity=0.046824, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2/22/2023 7:18 PM, Pasha Tatashin wrote: Hi Pasha, >> Coming from the virtio-pmem and some free page hinting background, I am >> interested in this discussion. I saw your proposal about single owner >> memory driver in other thread and could not entirely link the dots about >> applicability of the idea with "reducing the memory footprint overhead >> for virtual machines". Do we plan to co-ordinate guest memory state with >> corresponding host state for efficient memory reclaim decisions? >> Or something entirely different we are targeting here? > > Hi Pankaj, > > The plan is to have a driver /dev/memctl and corresponding VMM agent > that synchronously passes information about how guest would like its > memory to be backed on the host. > > For example the following information can come from guest for a range > of physical addresses: > MADV_NOHUGEPAGE > MADV_HUGEPAGE > MADV_DONTNEED > PR_SET_VMA_ANON_NAME > etc. > > All together this should help by doing memory management operations > only on the host side, and reduce the number of operations that are > performed on the guest. o.k. That sounds like guest will have a *special* interface (paravirt?) for some of the memory management operations with the coordination of host. Guest would still allow other regular memory operations? which would get full-filled by the guest? Just wondering if this solution only be useful for specific workloads which are aware of known MADV calls? And might not do/require continuous allocation/deallocation of memory? Thanks, Pankaj > > The /dev/som can help with allowing support for anonymous memory in > the guest with 1G pages that are only partially backed on the host > side, thus yielding to faster guestVA hostPA translations. > > Pasha