From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from max.phys.uu.nl (max.phys.uu.nl [131.211.32.73]) by kvack.org (8.8.7/8.8.7) with ESMTP id MAA06566 for ; Thu, 3 Dec 1998 12:58:39 -0500 Date: Thu, 3 Dec 1998 18:56:34 +0100 (CET) From: Rik van Riel Reply-To: Rik van Riel Subject: [PATCH] swapin readahead and fixes Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Linux MM Cc: Linux Kernel List-ID: Hi, here is a patch (against 2.1.130, but vs. 2.1.131 should be trivial) that improves the swapping performance both during swapout and swapin and contains a few minor fixes. The swapout enhancement is in the fact that now kswapd tries to free memory when it has a few swapout requests pending in order to avoid a swapout frenzy -- and also without avoiding too much pressure on the caches. The swapin enhancement consists of a simple swapin readahead. I have extensively tortured this version of the patch and it should survive the most extreme things now. It is only a primitive readahead thingy and can probably be improved quite a lot; that, however, is something to do later when it is proven stable and the bugfix parts are included in the kernel. Future versions of this (and other) patches can be grabbed from http://linux-patches.rock-projects.com/ or from my home page... check out Linux-patches! regards, Rik -- the flu hits, the flu hits, the flu hits -- MORE +-------------------------------------------------------------------+ | Linux memory management tour guide. H.H.vanRiel@phys.uu.nl | | Scouting Vries cubscout leader. http://www.phys.uu.nl/~riel/ | +-------------------------------------------------------------------+ --- ./mm/vmscan.c.orig Thu Nov 26 11:26:50 1998 +++ ./mm/vmscan.c Tue Dec 1 07:12:28 1998 @@ -431,6 +431,8 @@ kmem_cache_reap(gfp_mask); if (buffer_over_borrow() || pgcache_over_borrow()) + state = 0; + if (atomic_read(&nr_async_pages) > pager_daemon.swap_cluster / 2) shrink_mmap(i, gfp_mask); switch (state) { --- ./mm/page_io.c.orig Thu Nov 26 11:26:49 1998 +++ ./mm/page_io.c Thu Nov 26 11:30:43 1998 @@ -60,7 +60,7 @@ } /* Don't allow too many pending pages in flight.. */ - if (atomic_read(&nr_async_pages) > SWAP_CLUSTER_MAX) + if (atomic_read(&nr_async_pages) > pager_daemon.swap_cluster) wait = 1; p = &swap_info[type]; --- ./mm/page_alloc.c.orig Thu Nov 26 11:26:49 1998 +++ ./mm/page_alloc.c Thu Dec 3 15:40:48 1998 @@ -370,9 +370,32 @@ pte_t * page_table, unsigned long entry, int write_access) { unsigned long page; - struct page *page_map; - + int i; + struct page *new_page, *page_map = lookup_swap_cache(entry); + unsigned long offset = SWP_OFFSET(entry); + struct swap_info_struct *swapdev = SWP_TYPE(entry) + swap_info; + + if (!page_map) { page_map = read_swap_cache(entry); + + /* + * Primitive swap readahead code. We simply read the + * next 16 entries in the swap area. The break below + * is needed or else the request queue will explode :) + */ + for (i = 1; i++ < 16;) { + offset++; + if (!swapdev->swap_map[offset] || offset >= swapdev->max + || nr_free_pages - atomic_read(&nr_async_pages) < + (freepages.high + freepages.low)/2) + break; + if (test_bit(offset, swapdev->swap_lockmap)) + continue; + new_page = read_swap_cache_async(SWP_ENTRY(SWP_TYPE(entry), offset), 0); + if (new_page != NULL) + __free_page(new_page); + } + } if (pte_val(*page_table) != entry) { if (page_map) --- ./mm/swap_state.c.orig Thu Nov 26 11:26:49 1998 +++ ./mm/swap_state.c Thu Dec 3 15:40:34 1998 @@ -258,9 +258,10 @@ * incremented. */ -static struct page * lookup_swap_cache(unsigned long entry) +struct page * lookup_swap_cache(unsigned long entry) { struct page *found; + swap_cache_find_total++; while (1) { found = find_page(&swapper_inode, entry); @@ -268,8 +269,10 @@ return 0; if (found->inode != &swapper_inode || !PageSwapCache(found)) goto out_bad; - if (!PageLocked(found)) + if (!PageLocked(found)) { + swap_cache_find_success++; return found; + } __free_page(found); __wait_on_page(found); } --- ./include/linux/swap.h.orig Tue Dec 1 07:29:56 1998 +++ ./include/linux/swap.h Tue Dec 1 07:31:03 1998 @@ -90,6 +90,7 @@ extern struct page * read_swap_cache_async(unsigned long, int); #define read_swap_cache(entry) read_swap_cache_async(entry, 1); extern int FASTCALL(swap_count(unsigned long)); +extern struct page * lookup_swap_cache(unsigned long); /* * Make these inline later once they are working properly. */ -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org