From e98337d11bbdfa3e3f0fb99aa93e40f97549e0cd Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Tue, 13 Aug 2024 21:54:49 -0600 Subject: mm/contig_alloc: support __GFP_COMP Patch series "mm/hugetlb: alloc/free gigantic folios", v2. Use __GFP_COMP for gigantic folios can greatly reduce not only the amount of code but also the allocation and free time. Approximate LOC to mm/hugetlb.c: +60, -240 Allocate and free 500 1GB hugeTLB memory without HVO by: time echo 500 >/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages time echo 0 >/sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages Before After Alloc ~13s ~10s Free ~15s <1s The above magnitude generally holds for multiple x86 and arm64 CPU models. Perf profile before: Alloc - 99.99% alloc_pool_huge_folio - __alloc_fresh_hugetlb_folio - 83.23% alloc_contig_pages_noprof - 47.46% alloc_contig_range_noprof - 20.96% isolate_freepages_range 16.10% split_page - 14.10% start_isolate_page_range - 12.02% undo_isolate_page_range Free - update_and_free_pages_bulk - 87.71% free_contig_range - 76.02% free_unref_page - 41.30% free_unref_page_commit - 32.58% free_pcppages_bulk - 24.75% __free_one_page 13.96% _raw_spin_trylock 12.27% __update_and_free_hugetlb_folio Perf profile after: Alloc - 99.99% alloc_pool_huge_folio alloc_gigantic_folio - alloc_contig_pages_noprof - 59.15% alloc_contig_range_noprof - 20.72% start_isolate_page_range 20.64% prep_new_page - 17.13% undo_isolate_page_range Free - update_and_free_pages_bulk - __folio_put - __free_pages_ok 7.46% free_tail_page_prepare - 1.97% free_one_page 1.86% __free_one_page This patch (of 3): Support __GFP_COMP in alloc_contig_range(). When the flag is set, upon success the function returns a large folio prepared by prep_new_page(), rather than a range of order-0 pages prepared by split_free_pages() (which is renamed from split_map_pages()). alloc_contig_range() can be used to allocate folios larger than MAX_PAGE_ORDER, e.g., gigantic hugeTLB folios. So on the free path, free_one_page() needs to handle that by split_large_buddy(). [akpm@linux-foundation.org: fix folio_alloc_gigantic_noprof() WARN expression, per Yu Liao] Link: https://lkml.kernel.org/r/20240814035451.773331-1-yuzhao@google.com Link: https://lkml.kernel.org/r/20240814035451.773331-2-yuzhao@google.com Signed-off-by: Yu Zhao Acked-by: Zi Yan Cc: Matthew Wilcox (Oracle) Cc: Muchun Song Cc: Frank van der Linden Signed-off-by: Andrew Morton --- include/linux/gfp.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'include') diff --git a/include/linux/gfp.h b/include/linux/gfp.h index f53f76e0b17e..03ba9563c6db 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -446,4 +446,27 @@ extern struct page *alloc_contig_pages_noprof(unsigned long nr_pages, gfp_t gfp_ #endif void free_contig_range(unsigned long pfn, unsigned long nr_pages); +#ifdef CONFIG_CONTIG_ALLOC +static inline struct folio *folio_alloc_gigantic_noprof(int order, gfp_t gfp, + int nid, nodemask_t *node) +{ + struct page *page; + + if (WARN_ON(!order || !(gfp & __GFP_COMP))) + return NULL; + + page = alloc_contig_pages_noprof(1 << order, gfp, nid, node); + + return page ? page_folio(page) : NULL; +} +#else +static inline struct folio *folio_alloc_gigantic_noprof(int order, gfp_t gfp, + int nid, nodemask_t *node) +{ + return NULL; +} +#endif +/* This should be paired with folio_put() rather than free_contig_range(). */ +#define folio_alloc_gigantic(...) alloc_hooks(folio_alloc_gigantic_noprof(__VA_ARGS__)) + #endif /* __LINUX_GFP_H */ -- cgit v1.2.3