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authorRik van Riel <riel@redhat.com>2012-03-21 16:33:50 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-21 17:54:56 -0700
commit67f96aa252e606cdf6c3cf1032952ec207ec0cf0 (patch)
treea5a4299dd32789831eda558b51c0120272846664 /include/linux/swap.h
parentc38446cc65e1f2b3eb8630c53943b94c4f65f670 (diff)
mm: make swapin readahead skip over holes
Ever since abandoning the virtual scan of processes, for scalability reasons, swap space has been a little more fragmented than before. This can lead to the situation where a large memory user is killed, swap space ends up full of "holes" and swapin readahead is totally ineffective. On my home system, after killing a leaky firefox it took over an hour to page just under 2GB of memory back in, slowing the virtual machines down to a crawl. This patch makes swapin readahead simply skip over holes, instead of stopping at them. This allows the system to swap things back in at rates of several MB/second, instead of a few hundred kB/second. The checks done in valid_swaphandles are already done in read_swap_cache_async as well, allowing us to remove a fair amount of code. [akpm@linux-foundation.org: fix it for page_cluster >= 32] Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Adrian Drzewiecki <z@drze.net> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/swap.h')
-rw-r--r--include/linux/swap.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 3e60228e7299..64a7dba67840 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -329,7 +329,6 @@ extern long total_swap_pages;
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(void);
extern swp_entry_t get_swap_page_of_type(int);
-extern int valid_swaphandles(swp_entry_t, unsigned long *);
extern int add_swap_count_continuation(swp_entry_t, gfp_t);
extern void swap_shmem_alloc(swp_entry_t);
extern int swap_duplicate(swp_entry_t);