Hi,
the following patch frees up swap space on swapin when
the swap area gets full.
This increases effective VM area from max(ram, swap)
all the way to memory = ram + swap.
Please apply for the next pre-kernel,
Rik('s fictional cronjob)
-- IA64: a worthy successor to i860.http://www.surriel.com/ http://distro.conectiva.com/
--- linux-2.4.7-ac7/mm/memory.c.orig Mon Aug 6 12:23:33 2001 +++ linux-2.4.7-ac7/mm/memory.c Tue Aug 7 14:20:11 2001 @@ -1147,6 +1147,20 @@ swap_free(entry); if (write_access && exclusive_swap_page(page)) pte = pte_mkwrite(pte_mkdirty(pte)); + + /* + * If swap space is getting low and we were the last user + * of this piece of swap space, we free this space so + * somebody else can be swapped out. + * + * We are protected against try_to_swap_out() because the + * page is locked and against do_fork() because we have + * read_lock(&mm->mmap_sem). + */ + if (vm_swap_full() && exclusive_swap_page(page)) { + delete_from_swap_cache_nolock(page); + pte = pte_mkwrite(pte_mkdirty(pte)); + } UnlockPage(page);
flush_page_to_ram(page); --- linux-2.4.7-ac7/mm/swapfile.c.orig Mon Aug 6 12:23:33 2001 +++ linux-2.4.7-ac7/mm/swapfile.c Tue Aug 7 11:55:18 2001 @@ -19,11 +19,34 @@
spinlock_t swaplock = SPIN_LOCK_UNLOCKED; unsigned int nr_swapfiles; +int total_swap_pages;
struct swap_list_t swap_list = {-1, -1};
struct swap_info_struct swap_info[MAX_SWAPFILES];
+/* + * When swap space gets filled up, we will set this flag. + * This will make do_swap_page(), in the page fault path, + * free swap entries on swapin so we'll reclaim swap space + * in order to be able to swap something out. + * + * At the moment we start reclaiming when swap usage goes + * over 80% of swap space and we continue reclaiming until + * the amount of occupied swap drops to less than 75%. + * XXX: these are random numbers, fixme. + */ +#define SWAP_FULL_PCT 80 +int vm_swap_full (void) { + int full = 0; + int swap_used = total_swap_pages - nr_swap_pages; + + if (swap_used * 100 > total_swap_pages * SWAP_FULL_PCT) + full = 1; + + return full; +} + #define SWAPFILE_CLUSTER 256
static inline int scan_swap_map(struct swap_info_struct *si, unsigned short count) @@ -469,6 +492,7 @@ swap_list.next = swap_list.head; } nr_swap_pages -= p->pages; + total_swap_pages -= p->pages; swap_list_unlock(); p->flags = SWP_USED; err = try_to_unuse(type); @@ -484,6 +508,7 @@ else swap_info[prev].next = p - swap_info; nr_swap_pages += p->pages; + total_swap_pages += p->pages; swap_list_unlock(); p->flags = SWP_WRITEOK; goto out_dput; @@ -771,6 +796,7 @@ p->pages = nr_good_pages; swap_list_lock(); nr_swap_pages += nr_good_pages; + total_swap_pages += nr_good_pages; printk(KERN_INFO "Adding Swap: %dk swap-space (priority %d)\n", nr_good_pages<<(PAGE_SHIFT-10), p->prio);
--- linux-2.4.7-ac7/include/linux/swap.h.orig Mon Aug 6 12:33:35 2001 +++ linux-2.4.7-ac7/include/linux/swap.h Mon Aug 6 20:08:44 2001 @@ -158,6 +158,7 @@ extern void free_page_and_swap_cache(struct page *page);
/* linux/mm/swapfile.c */ +extern int vm_swap_full(void); extern unsigned int nr_swapfiles; extern struct swap_info_struct swap_info[]; extern int is_swap_partition(kdev_t);
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This archive was generated by hypermail 2b29 : Wed Aug 15 2001 - 21:00:32 EST