vm - swap prefetch v14

Index: linux-2.6.13-sp/include/linux/swap.h
===================================================================
@@ -185,6 +185,38 @@ extern int shmem_unuse(swp_entry_t entry
 
 extern void swap_unplug_io_fn(struct backing_dev_info *, struct page *);
 
+#ifdef CONFIG_SWAP_PREFETCH
+/* only used by prefetch externally */
+/*	mm/swap_prefetch.c */
+extern void prepare_prefetch(void);
+extern void add_to_swapped_list(unsigned long index);
+extern void remove_from_swapped_list(unsigned long index);
+extern void delay_prefetch(void);
+/* linux/mm/page_alloc.c */
+extern struct page *
+buffered_rmqueue(struct zone *zone, int order, unsigned int __nocast gfp_flags);
+extern void zone_statistics(struct zonelist *zonelist, struct zone *z);
+extern int swap_prefetch;
+
+#else	/* CONFIG_SWAP_PREFETCH */
+static inline void add_to_swapped_list(unsigned long index)
+{
+}
+
+static inline void prepare_prefetch(void)
+{
+}
+
+static inline void remove_from_swapped_list(unsigned long index)
+{
+}
+
+static inline void delay_prefetch(void)
+{
+}
+
+#endif	/* CONFIG_SWAP_PREFETCH */
+
 #ifdef CONFIG_SWAP
 /* linux/mm/page_io.c */
 extern int swap_readpage(struct file *, struct page *);

@@ -206,6 +238,7 @@ extern void free_pages_and_swap_cache(st
 extern struct page * lookup_swap_cache(swp_entry_t);
 extern struct page * read_swap_cache_async(swp_entry_t, struct vm_area_struct *vma,
 					   unsigned long addr);
+extern int add_to_swap_cache(struct page *page, swp_entry_t entry);
 /* linux/mm/swapfile.c */
 extern long total_swap_pages;
 extern unsigned int nr_swapfiles;

Index: linux-2.6.13-sp/include/linux/sysctl.h
===================================================================
@@ -180,6 +180,7 @@ enum
 	VM_VFS_CACHE_PRESSURE=26, /* dcache/icache reclaim pressure */
 	VM_LEGACY_VA_LAYOUT=27, /* legacy/compatibility virtual address space layout */
 	VM_SWAP_TOKEN_TIMEOUT=28, /* default time for token time out */
+	VM_SWAP_PREFETCH=29,	/* int: amount to swap prefetch */
 };
 
 

Index: linux-2.6.13-sp/kernel/sysctl.c
===================================================================
@@ -850,6 +850,18 @@ static ctl_table vm_table[] = {
 		.proc_handler	= &proc_dointvec_jiffies,
 		.strategy	= &sysctl_jiffies,
 	},
+#ifdef CONFIG_SWAP_PREFETCH
+	{
+		.ctl_name	= VM_SWAP_PREFETCH,
+		.procname	= "swap_prefetch",
+		.data		= &swap_prefetch,
+		.maxlen		= sizeof(swap_prefetch),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec,
+		.strategy	= &sysctl_intvec,
+		.extra1		= &zero,
+	},
+#endif
 #endif
 	{ .ctl_name = 0 }
 };

Index: linux-2.6.13-sp/mm/page_alloc.c
===================================================================
@@ -607,7 +607,7 @@ void drain_local_pages(void)
 }
 #endif /* CONFIG_PM */
 
-static void zone_statistics(struct zonelist *zonelist, struct zone *z)
+void zone_statistics(struct zonelist *zonelist, struct zone *z)
 {
 #ifdef CONFIG_NUMA
 	unsigned long flags;

@@ -684,7 +684,7 @@ static inline void prep_zero_page(struct
  * we cheat by calling it from here, in the order > 0 path.  Saves a branch
  * or two.
  */
-static struct page *
+struct page *
 buffered_rmqueue(struct zone *zone, int order, unsigned int __nocast gfp_flags)
 {
 	unsigned long flags;

@@ -745,7 +745,7 @@ int zone_watermark_ok(struct zone *z, in
 		min -= min / 4;
 
 	if (free_pages <= min + z->lowmem_reserve[classzone_idx])
-		return 0;
+		goto out_failed;
 	for (o = 0; o < order; o++) {
 		/* At the next order, this order's pages become unavailable */
 		free_pages -= z->free_area[o].nr_free << o;

@@ -754,9 +754,15 @@ int zone_watermark_ok(struct zone *z, in
 		min >>= 1;
 
 		if (free_pages <= min)
-			return 0;
+			goto out_failed;
 	}
+
 	return 1;
+out_failed:
+	/* Swap prefetching is delayed if any watermark is low */
+	delay_prefetch();
+
+	return 0;	
 }
 
 static inline int

Index: linux-2.6.13-sp/mm/swap.c
===================================================================
@@ -481,5 +481,8 @@ void __init swap_setup(void)
 	 * Right now other parts of the system means that we
 	 * _really_ don't want to cluster much more
 	 */
+
+	prepare_prefetch();
+
 	hotcpu_notifier(cpu_swap_callback, 0);
 }

434 lines not on this page · raw message

Index: linux-2.6.13-sp/mm/swap_state.c
===================================================================
@@ -80,6 +80,7 @@ static int __add_to_swap_cache(struct pa
 		error = radix_tree_insert(&swapper_space.page_tree,
 						entry.val, page);
 		if (!error) {
+			remove_from_swapped_list(entry.val);
 			page_cache_get(page);
 			SetPageLocked(page);
 			SetPageSwapCache(page);

@@ -93,11 +94,12 @@ static int __add_to_swap_cache(struct pa
 	return error;
 }
 
-static int add_to_swap_cache(struct page *page, swp_entry_t entry)
+int add_to_swap_cache(struct page *page, swp_entry_t entry)
 {
 	int error;
 
 	if (!swap_duplicate(entry)) {
+		remove_from_swapped_list(entry.val);
 		INC_CACHE_INFO(noent_race);
 		return -ENOENT;
 	}

@@ -145,6 +147,9 @@ int add_to_swap(struct page * page)
 	swp_entry_t entry;
 	int err;
 
+	/* Swap prefetching is delayed if we're swapping pages */
+	delay_prefetch();
+
 	if (!PageLocked(page))
 		BUG();
 

@@ -325,6 +330,9 @@ struct page *read_swap_cache_async(swp_e
 	struct page *found_page, *new_page = NULL;
 	int err;
 
+	/* Swap prefetching is delayed if we're already reading from swap */
+	delay_prefetch();
+
 	do {
 		/*
 		 * First check the swap cache.  Since this is normally

Index: linux-2.6.13-sp/mm/vmscan.c
===================================================================
@@ -519,6 +519,7 @@ static int shrink_list(struct list_head 
 #ifdef CONFIG_SWAP
 		if (PageSwapCache(page)) {
 			swp_entry_t swap = { .val = page->private };
+			add_to_swapped_list(swap.val);
 			__delete_from_swap_cache(page);
 			write_unlock_irq(&mapping->tree_lock);
 			swap_free(swap);

@@ -929,6 +930,8 @@ int try_to_free_pages(struct zone **zone
 	unsigned long lru_pages = 0;
 	int i;
 
+	delay_prefetch();
+
 	sc.gfp_mask = gfp_mask;
 	sc.may_writepage = 0;
 	sc.may_swap = 1;

@@ -1275,6 +1278,8 @@ int shrink_all_memory(int nr_pages)
 		.reclaimed_slab = 0,
 	};
 
+	delay_prefetch();
+
 	current->reclaim_state = &reclaim_state;
 	for_each_pgdat(pgdat) {
 		int freed;