On Thu, Mar 12, 2020 at 09:37:32AM +0100, David Hildenbrand wrote: > 2. You are essentially stealing THPs in the guest. So the fastest > mapping (THP in guest and host) is gone. The guest won't be able to make > use of THP where it previously was able to. I can imagine this implies a > performance degradation for some workloads. This needs a proper > performance evaluation. I think the problem is more with the alloc_pages API. That gives you exactly the given order, and if there's a larger chunk available, it will split it up. But for balloon - I suspect lots of other users, we do not want to stress the system but if a large chunk is available anyway, then we could handle that more optimally by getting it all in one go. So if we want to address this, IMHO this calls for a new API. Along the lines of struct page *alloc_page_range(gfp_t gfp, unsigned int min_order, unsigned int max_order, unsigned int *order) the idea would then be to return at a number of pages in the given range. What do you think? Want to try implementing that? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
