From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx> Subject: mm: optimise put_pages_list() Instead of calling put_page() one page at a time, pop pages off the list if their refcount was too high and pass the remainder to put_unref_page_list(). This should be a speed improvement, but I have no measurements to support that. Current callers do not care about performance, but I hope to add some which do. Link: https://lkml.kernel.org/r/20211007192138.561673-1-willy@xxxxxxxxxxxxx Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/swap.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-) --- a/mm/swap.c~mm-optimise-put_pages_list +++ a/mm/swap.c @@ -134,18 +134,27 @@ EXPORT_SYMBOL(__put_page); * put_pages_list() - release a list of pages * @pages: list of pages threaded on page->lru * - * Release a list of pages which are strung together on page.lru. Currently - * used by read_cache_pages() and related error recovery code. + * Release a list of pages which are strung together on page.lru. */ void put_pages_list(struct list_head *pages) { - while (!list_empty(pages)) { - struct page *victim; + struct page *page, *next; - victim = lru_to_page(pages); - list_del(&victim->lru); - put_page(victim); + list_for_each_entry_safe(page, next, pages, lru) { + if (!put_page_testzero(page)) { + list_del(&page->lru); + continue; + } + if (PageHead(page)) { + list_del(&page->lru); + __put_compound_page(page); + continue; + } + /* Cannot be PageLRU because it's passed to us using the lru */ + __ClearPageWaiters(page); } + + free_unref_page_list(pages); } EXPORT_SYMBOL(put_pages_list); _
