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 IAA05239 for ; Thu, 3 Dec 1998 08:42:07 -0500 Date: Thu, 3 Dec 1998 14:28:30 +0100 (CET) From: Rik van Riel Reply-To: Rik van Riel Subject: Re: [PATCH] swapin readahead v4 In-Reply-To: <199812031235.MAA03337@dax.scot.redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: "Stephen C. Tweedie" Cc: Linux MM List-ID: On Thu, 3 Dec 1998, Stephen C. Tweedie wrote: > > Stephen's messages gave away the clue to something I was just > > about to track down myself. Anyway, here is the 4th version of > > my swapin readahead patch. > > Much better to do this after calling read_swap_cache_async(): it's bad > policy to make the reference count of the page after calling this > function dependent on the arguments: that is a maintenance nightmare. > > Oh, and you _still_ need to check the swap_lockmap before calling > read_swap_cache_async(), and you still have the extra break() in the > readahead loop... Somebody forbid me to do coding while having a flu... This patch (v5) should be much better (I haven't tried it yet but it has all things Stephen told me to include -- as far as I can see through the haze that surrounds me). cheers, 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 14:26:25 1998 @@ -370,9 +370,31 @@ 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 || + test_bit(offset, swapdev->swap_lockmap)) + continue; + new_page = read_swap_cache_async(SWP_ENTRY(SWP_TYPE(entry), offset), 0); + if (new_page) + __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 14:19:19 1998 @@ -258,7 +258,7 @@ * incremented. */ -static struct page * lookup_swap_cache(unsigned long entry) +struct page * lookup_swap_cache(unsigned long entry) { struct 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