From 46017e954826ac59e91df76341a3f76b45467847 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 4 Feb 2008 22:28:41 -0800 Subject: swapin_readahead: move and rearrange args swapin_readahead has never sat well in mm/memory.c: move it to mm/swap_state.c beside its kindred read_swap_cache_async. Why were its args in a different order? rearrange them. And since it was always followed by a read_swap_cache_async of the target page, fold that in and return struct page*. Then CONFIG_SWAP=n no longer needs valid_swaphandles and read_swap_cache_async stubs. Signed-off-by: Hugh Dickins Acked-by: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swap_state.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'mm/swap_state.c') diff --git a/mm/swap_state.c b/mm/swap_state.c index b52635601df..668a8042263 100644 --- a/mm/swap_state.c +++ b/mm/swap_state.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -368,3 +369,49 @@ struct page *read_swap_cache_async(swp_entry_t entry, page_cache_release(new_page); return found_page; } + +/** + * swapin_readahead - swap in pages in hope we need them soon + * @entry: swap entry of this memory + * @vma: user vma this address belongs to + * @addr: target address for mempolicy + * + * Returns the struct page for entry and addr, after queueing swapin. + * + * Primitive swap readahead code. We simply read an aligned block of + * (1 << page_cluster) entries in the swap area. This method is chosen + * because it doesn't cost us any seek time. We also make sure to queue + * the 'original' request together with the readahead ones... + * + * This has been extended to use the NUMA policies from the mm triggering + * the readahead. + * + * Caller must hold down_read on the vma->vm_mm if vma is not NULL. + */ +struct page *swapin_readahead(swp_entry_t entry, + struct vm_area_struct *vma, unsigned long addr) +{ + int nr_pages; + struct page *page; + unsigned long offset; + unsigned long end_offset; + + /* + * Get starting offset for readaround, and number of pages to read. + * Adjust starting address by readbehind (for NUMA interleave case)? + * No, it's very unlikely that swap layout would follow vma layout, + * more likely that neighbouring swap pages came from the same node: + * so use the same "addr" to choose the same node for each swap read. + */ + nr_pages = valid_swaphandles(entry, &offset); + for (end_offset = offset + nr_pages; offset < end_offset; offset++) { + /* Ok, do the async read-ahead now */ + page = read_swap_cache_async(swp_entry(swp_type(entry), offset), + vma, addr); + if (!page) + break; + page_cache_release(page); + } + lru_add_drain(); /* Push any new pages onto the LRU now */ + return read_swap_cache_async(entry, vma, addr); +} -- cgit v1.2.3