On 20.06.2017 18:44, Rik van Riel wrote: > On Mon, 2017-06-12 at 07:10 -0700, Dave Hansen wrote: > >> The hypervisor is going to throw away the contents of these pages, >> right? As soon as the spinlock is released, someone can allocate a >> page, and put good data in it. What keeps the hypervisor from >> throwing >> away good data? > > That looks like it may be the wrong API, then? > > We already have hooks called arch_free_page and > arch_alloc_page in the VM, which are called when > pages are freed, and allocated, respectively. > > Nitesh Lal (on the CC list) is working on a way > to efficiently batch recently freed pages for > free page hinting to the hypervisor. > > If that is done efficiently enough (eg. with > MADV_FREE on the hypervisor side for lazy freeing, > and lazy later re-use of the pages), do we still > need the harder to use batch interface from this > patch? > David's opinion incoming: No, I think proper free page hinting would be the optimum solution, if done right. This would avoid the batch interface and even turn virtio-balloon in some sense useless. -- Thanks, David
