On Wed, Feb 22, 2023 at 04:55:20PM -0700, Yu Zhao wrote: > Currently anonymous folios only support two orders: 0 and the PMD > order. Flexible orders for anonymous folios can resist both internal > or external fragmentations when the PMD order is too underutilized or > costly to allocate. Flexible orders can also leverage the TLB > coalescing feature, .e.g., order 3 for AMD and order 4 for ARM CPUs. I'm interested in this too - we've started to look at using 64K as a base page size on ARM systems and having an order 3 folio would be the usual 2M "THP" size with the coalescing feature. Keeping THP is a desirable thing. We also have some IOMMU HW that can do flexible orders, so even if the CPU TLB cannot store odd folio sizes the IOMMU TLB can, which can be interesting for KVM & VFIO. Thanks, Jason
