On Sat, Apr 23, 2016 at 10:46 PM, Wincy Van <fanwenyi0...@gmail.com> wrote: > On Wed, Apr 20, 2016 at 1:07 AM, Andres Lagar-Cavilla > <andre...@google.com> wrote: >> Andrea, we provide the, ahem, adjustments to >> transparent_hugepage_adjust. Rest assured we aggressively use mmu >> notifiers with no further changes required. >> >> As in: zero changes have been required in the lifetime (years) of >> kvm+huge tmpfs at Google, other than mod'ing >> transparent_hugepage_adjust. > > We are using kvm + tmpfs to do qemu live upgrading, how does google > use this memory model ? > I think our pupose to use tmpfs may be the same.
Nothing our of the ordinary. Guest memory is an mmap of a tmpfs fd. Huge tmpfs gives us naturally a great guest performance boost. MAP_SHARED, and having guest memory persist any one given process, are what drives us to use tmpfs. Andres > > And huge tmpfs is a really good improvement for that. > >> >> As noted by Paolo, the additions to transparent_hugepage_adjust could >> be lifted outside of kvm (into shmem.c? maybe) for any consumer of >> huge tmpfs with mmu notifiers. >> > > Thanks, > Wincy -- Andres Lagar-Cavilla | Google Kernel Team | andre...@google.com
