diff options
| -rw-r--r-- | mm/swapfile.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 8a6cdf9e55f9..811d90e1c929 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -37,6 +37,7 @@ #include <linux/swapfile.h> #include <linux/export.h> #include <linux/swap_slots.h> +#include <linux/sort.h> #include <asm/pgtable.h> #include <asm/tlbflush.h> @@ -1198,6 +1199,13 @@ void put_swap_page(struct page *page, swp_entry_t entry) swapcache_free_cluster(entry); } +static int swp_entry_cmp(const void *ent1, const void *ent2) +{ + const swp_entry_t *e1 = ent1, *e2 = ent2; + + return (int)swp_type(*e1) - (int)swp_type(*e2); +} + void swapcache_free_entries(swp_entry_t *entries, int n) { struct swap_info_struct *p, *prev; @@ -1208,6 +1216,14 @@ void swapcache_free_entries(swp_entry_t *entries, int n) prev = NULL; p = NULL; + + /* + * Sort swap entries by swap device, so each lock is only taken once. + * nr_swapfiles isn't absolutely correct, but the overhead of sort() is + * so low that it isn't necessary to optimize further. + */ + if (nr_swapfiles > 1) + sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); for (i = 0; i < n; ++i) { p = swap_info_get_cont(entries[i], prev); if (p) |