[PATCH 3/8] mm: Optimise madvise WILLNEED
From: Matthew Wilcox (Oracle) <hidden>
Date: 2020-08-19 18:49:15
Also in:
intel-gfx, linux-mm, lkml
Subsystem:
memory management, memory mapping - madvise (memory advice), the rest · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, David Hildenbrand, Linus Torvalds
Instead of calling find_get_entry() for every page index, use an XArray iterator to skip over NULL entries, and avoid calling get_page(), because we only want the swap entries. Signed-off-by: Matthew Wilcox (Oracle) <redacted> --- mm/madvise.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index dd1d43cf026d..96189acd6969 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c@@ -224,25 +224,28 @@ static void force_shm_swapin_readahead(struct vm_area_struct *vma, unsigned long start, unsigned long end, struct address_space *mapping) { - pgoff_t index; + XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start)); + pgoff_t end_index = end / PAGE_SIZE; struct page *page; - swp_entry_t swap; - for (; start < end; start += PAGE_SIZE) { - index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; + rcu_read_lock(); + xas_for_each(&xas, page, end_index) { + swp_entry_t swap; - page = find_get_entry(mapping, index); - if (!xa_is_value(page)) { - if (page) - put_page(page); + if (!xa_is_value(page)) continue; - } + rcu_read_unlock(); + swap = radix_to_swp_entry(page); page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE, NULL, 0, false); if (page) put_page(page); + + rcu_read_lock(); + xas_reset(&xas); } + rcu_read_unlock(); lru_add_drain(); /* Push any new pages onto the LRU now */ }
--
2.28.0