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authorDev Jain <dev.jain@arm.com>2025-06-10 09:20:43 +0530
committerAndrew Morton <akpm@linux-foundation.org>2025-07-09 22:42:07 -0700
commitf822a9a81a31311d67f260aea96005540b18ab07 (patch)
tree5edffe419cfb862d6c7002a282adf50dcea6135d /mm/madvise.c
parent94dab12d86cf77ff0b8f667dc98af6d997422cb4 (diff)
downloadtip-f822a9a81a31311d67f260aea96005540b18ab07.tar.gz
mm: optimize mremap() by PTE batching
Use folio_pte_batch() to optimize move_ptes(). On arm64, if the ptes are painted with the contig bit, then ptep_get() will iterate through all 16 entries to collect a/d bits. Hence this optimization will result in a 16x reduction in the number of ptep_get() calls. Next, ptep_get_and_clear() will eventually call contpte_try_unfold() on every contig block, thus flushing the TLB for the complete large folio range. Instead, use get_and_clear_full_ptes() so as to elide TLBIs on each contig block, and only do them on the starting and ending contig block. For split folios, there will be no pte batching; nr_ptes will be 1. For pagetable splitting, the ptes will still point to the same large folio; for arm64, this results in the optimization described above, and for other arches (including the general case), a minor improvement is expected due to a reduction in the number of function calls. Link: https://lkml.kernel.org/r/20250610035043.75448-3-dev.jain@arm.com Signed-off-by: Dev Jain <dev.jain@arm.com> Reviewed-by: Barry Song <baohua@kernel.org> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Reviewed-by: Pedro Falcato <pfalcato@suse.de> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Bang Li <libang.li@antgroup.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: bibo mao <maobibo@loongson.cn> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jann Horn <jannh@google.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Peter Xu <peterx@redhat.com> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <yang@os.amperecomputing.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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