If the region is for gigantic hugepages and if HVO is enabled, then those struct pages which will be freed later by HVO don't need to be prepared and initialized. This can save significant time when a large number of hugepages are allocated at boot time. For a 1G hugepage, this series avoid initialization and preparation of 262144 - 64 = 262080 struct pages per hugepage. When tested on a 512G system (which can allocate max 500 1G hugepages), the kexec-boot time with HVO and DEFERRED_STRUCT_PAGE_INIT enabled without this patchseries to running init is 3.9 seconds. With this patch it is 1.2 seconds. This represents an approximately 70% reduction in boot time and will significantly reduce server downtime when using a large number of gigantic pages. Thanks, Usama [v1->v2]: - (Mike Rapoport) Code quality improvements (function names, arguments, comments). [RFC->v1]: - (Mike Rapoport) Change from passing hugepage_size in memblock_alloc_try_nid_raw for skipping struct page initialization to using MEMBLOCK_RSRV_NOINIT flag Usama Arif (6): mm: hugetlb: Skip prep of tail pages when HVO is enabled mm: hugetlb_vmemmap: Use nid of the head page to reallocate it memblock: pass memblock_type to memblock_setclr_flag memblock: introduce MEMBLOCK_RSRV_NOINIT flag mm: move allocation of gigantic hstates to the start of mm_core_init mm: hugetlb: Skip initialization of struct pages freed later by HVO include/linux/memblock.h | 9 +++++ mm/hugetlb.c | 71 +++++++++++++++++++++++++--------------- mm/hugetlb_vmemmap.c | 6 ++-- mm/hugetlb_vmemmap.h | 18 +++++++--- mm/internal.h | 9 +++++ mm/memblock.c | 45 +++++++++++++++++-------- mm/mm_init.c | 6 ++++ 7 files changed, 118 insertions(+), 46 deletions(-) -- 2.25.1
