On Sun, Feb 26, 2023 at 09:30:31AM +0800, Hillf Danton wrote: > 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. > > > > Discussion points: > > 1. The page fault path: determining the best order and the fallback policy. > > 2. The reclaim path: detecting the utilization and the splitting policy. > > 3. The refcount and the mapcount models, e.g., reuse the PMD-mapped > > THP model or not. > > 4. The splitting, and the collapsing if needed. > > 5. Other paths: COW, GUP, madvise(), mprotect(), page migration, etc. > > 6. Given the number of TLB is farrr less than the number of pages, > what workload prefers MADV_ORDER6 over MADV_HUGEPAGE for instance? Many. https://lore.kernel.org/linux-mm/Y%2FWRlX+MkmxelNbg@xxxxxxxxxxxxxxxxxxxx/
