Re: Zoned CART

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

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On Sun, 2005-08-14 at 14:58 +0200, Peter Zijlstra wrote:

> 
> Ok, now on to putting Rahul code on top of this ;-)

I got UML to boot with this patch. Now for some stress and behavioural
testing.
 
 include/linux/cart.h       |   12 ++
 include/linux/mm_inline.h  |   36 ++++++
 include/linux/mmzone.h     |   12 +-
 include/linux/page-flags.h |    5
 include/linux/swap.h       |   14 ++
 init/main.c                |    5
 mm/Makefile                |    3
 mm/cart.c                  |  175 +++++++++++++++++++++++++++++++
 mm/nonresident.c           |  251 +++++++++++++++++++++++++++++++++++++++++++++
 mm/swap.c                  |    4
 mm/vmscan.c                |   43 +++++++
 11 files changed, 553 insertions(+), 7 deletions(-)

-- 
Peter Zijlstra <a.p.zijlstra@chello.nl>

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diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/include/linux/cart.h linux-2.6.13-rc6-cart/include/linux/cart.h
--- linux-2.6.13-rc6/include/linux/cart.h	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.13-rc6-cart/include/linux/cart.h	2005-08-15 17:33:07.000000000 +0200
@@ -0,0 +1,12 @@
+#ifndef __CART_H__
+#define __CART_H__
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+
+extern void cart_init(void);
+extern void update_cart_params(struct page *);
+extern struct page *replace(struct zone *, unsigned int *);
+
+#endif
+
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/include/linux/mm_inline.h linux-2.6.13-rc6-cart/include/linux/mm_inline.h
--- linux-2.6.13-rc6/include/linux/mm_inline.h	2005-03-02 08:38:33.000000000 +0100
+++ linux-2.6.13-rc6-cart/include/linux/mm_inline.h	2005-08-15 17:33:07.000000000 +0200
@@ -38,3 +38,39 @@ del_page_from_lru(struct zone *zone, str
 		zone->nr_inactive--;
 	}
 }
+
+static inline void
+add_page_to_active_tail(struct zone *zone, struct page *page)
+{
+	list_add_tail(&page->lru, &zone->active_list);
+	zone->nr_active++;
+}
+
+static inline void 
+del_page_from_active(struct zone *zone, struct page *page)
+{
+	list_del(&page->lru);
+	zone->nr_active--;
+}
+
+static inline void
+add_page_to_inactive_tail(struct zone *zone, struct page *page)
+{
+        list_add_tail(&page->lru, &zone->inactive_list);
+        zone->nr_inactive++;
+}
+
+static inline void 
+del_page_from_active_longterm(struct zone *zone, struct page *page)
+{
+	list_del(&page->lru);
+	zone->nr_active_longterm--;
+}
+
+static inline void
+add_page_to_active_longterm_tail(struct zone *zone, struct page *page)
+{
+	list_add_tail(&page->lru, &zone->active_longterm);
+	zone->nr_active_longterm++;
+}
+
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/include/linux/mmzone.h linux-2.6.13-rc6-cart/include/linux/mmzone.h
--- linux-2.6.13-rc6/include/linux/mmzone.h	2005-08-15 22:37:00.000000000 +0200
+++ linux-2.6.13-rc6-cart/include/linux/mmzone.h	2005-08-15 17:33:07.000000000 +0200
@@ -144,12 +144,20 @@ struct zone {
 
 	/* Fields commonly accessed by the page reclaim scanner */
 	spinlock_t		lru_lock;	
-	struct list_head	active_list;
+	struct list_head	active_list;	/* The T1 list of CART */
+	struct list_head	active_longterm;/* The T2 list of CART */
 	struct list_head	inactive_list;
 	unsigned long		nr_scan_active;
 	unsigned long		nr_scan_inactive;
-	unsigned long		nr_active;
+	unsigned long		nr_active;	
+	unsigned long		nr_active_longterm;
 	unsigned long		nr_inactive;
+	unsigned long 		nr_evicted_active;
+	unsigned long 		nr_evicted_longterm;
+	unsigned long 		nr_longterm;	/* number of long term pages */
+	unsigned long 		nr_shortterm;	/* number of short term pages */
+	unsigned long		cart_p;		/* p from the CART paper */
+	unsigned long 		cart_q;		/* q from the cart paper */
 	unsigned long		pages_scanned;	   /* since last reclaim */
 	int			all_unreclaimable; /* All pages pinned */
 
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/include/linux/page-flags.h linux-2.6.13-rc6-cart/include/linux/page-flags.h
--- linux-2.6.13-rc6/include/linux/page-flags.h	2005-08-15 22:37:00.000000000 +0200
+++ linux-2.6.13-rc6-cart/include/linux/page-flags.h	2005-08-15 17:33:07.000000000 +0200
@@ -75,6 +75,7 @@
 #define PG_reclaim		17	/* To be reclaimed asap */
 #define PG_nosave_free		18	/* Free, should not be written */
 #define PG_uncached		19	/* Page has been mapped as uncached */
+#define PG_longterm		20	/* Filter bit for CART see mm/cart.c */
 
 /*
  * Global page accounting.  One instance per CPU.  Only unsigned longs are
@@ -305,6 +306,10 @@ extern void __mod_page_state(unsigned lo
 #define SetPageUncached(page)	set_bit(PG_uncached, &(page)->flags)
 #define ClearPageUncached(page)	clear_bit(PG_uncached, &(page)->flags)
 
+#define PageLongTerm(page)	test_bit(PG_longterm, &(page)->flags)
+#define SetLongTerm(page)	set_bit(PG_longterm, &(page)->flags)
+#define ClearLongTerm(page)	clear_bit(PG_longterm, &(page)->flags)
+
 struct page;	/* forward declaration */
 
 int test_clear_page_dirty(struct page *page);
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/include/linux/swap.h linux-2.6.13-rc6-cart/include/linux/swap.h
--- linux-2.6.13-rc6/include/linux/swap.h	2005-08-15 22:37:00.000000000 +0200
+++ linux-2.6.13-rc6-cart/include/linux/swap.h	2005-08-15 17:33:08.000000000 +0200
@@ -154,6 +154,15 @@ extern void out_of_memory(unsigned int _
 /* linux/mm/memory.c */
 extern void swapin_readahead(swp_entry_t, unsigned long, struct vm_area_struct *);
 
+/* linux/mm/nonresident.c */
+#define NR_filter		0x01  /* short/long */
+#define NR_list			0x02  /* b1/b2; correlates to PG_active */
+#define NR_evict		0x80000000
+
+extern u32 remember_page(struct address_space *, unsigned long, unsigned int);
+extern unsigned int recently_evicted(struct address_space *, unsigned long);
+extern void init_nonresident(void);
+
 /* linux/mm/page_alloc.c */
 extern unsigned long totalram_pages;
 extern unsigned long totalhigh_pages;
@@ -292,6 +301,11 @@ static inline swp_entry_t get_swap_page(
 #define grab_swap_token()  do { } while(0)
 #define has_swap_token(x) 0
 
+/* linux/mm/nonresident.c */
+#define init_nonresident()	do { } while (0)
+#define remember_page(x,y,z)	0
+#define recently_evicted(x,y)	0
+
 #endif /* CONFIG_SWAP */
 #endif /* __KERNEL__*/
 #endif /* _LINUX_SWAP_H */
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/init/main.c linux-2.6.13-rc6-cart/init/main.c
--- linux-2.6.13-rc6/init/main.c	2005-08-15 22:37:00.000000000 +0200
+++ linux-2.6.13-rc6-cart/init/main.c	2005-08-15 17:36:19.000000000 +0200
@@ -47,12 +47,15 @@
 #include <linux/rmap.h>
 #include <linux/mempolicy.h>
 #include <linux/key.h>
+#include <linux/swap.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>
 #include <asm/setup.h>
 #include <asm/sections.h>
 
+#include <linux/cart.h>
+
 /*
  * This is one of the first .c files built. Error out early
  * if we have compiler trouble..
@@ -494,7 +497,9 @@ asmlinkage void __init start_kernel(void
 	}
 #endif
 	vfs_caches_init_early();
+	init_nonresident();
 	mem_init();
+	cart_init();
 	kmem_cache_init();
 	setup_per_cpu_pageset();
 	numa_policy_init();
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/mm/Makefile linux-2.6.13-rc6-cart/mm/Makefile
--- linux-2.6.13-rc6/mm/Makefile	2005-08-15 22:37:01.000000000 +0200
+++ linux-2.6.13-rc6-cart/mm/Makefile	2005-08-15 17:33:08.000000000 +0200
@@ -12,7 +12,8 @@ obj-y			:= bootmem.o filemap.o mempool.o
 			   readahead.o slab.o swap.o truncate.o vmscan.o \
 			   prio_tree.o $(mmu-y)
 
-obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o \
+			   nonresident.o cart.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/mm/cart.c linux-2.6.13-rc6-cart/mm/cart.c
--- linux-2.6.13-rc6/mm/cart.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.13-rc6-cart/mm/cart.c	2005-08-15 22:22:26.000000000 +0200
@@ -0,0 +1,175 @@
+/* Thisfile contains the crux of the CART page replacement algorithm. This implementation however changes a few things form the classic CART scheme. This implementation splits the original active_list of the Linux implementation into two lists, namely active_list and active_longterm. The 'active' pages exist on these two lists. The active_list hopes to capture short term usage, while the active_longterm list hopes to capture long term usage. Whenever a page's state needs to be updated, the update_cart_params() function is called. The refill_incative_zone() function causes the replace() function to be evoked, resulting in the removal of pages from the active lists. Hence, which pages are deemed inactive is determined by the CART algorithm. 
+For further details, please refer to the CART paper here - http://www.almaden.ibm.com/cs/people/dmodha/clockfast.pdf */
+ 
+#include <linux/cart.h>
+#include <linux/page-flags.h>
+#include <linux/mm_inline.h>
+
+/* Called from init/main.c to initialize the cart parameters */
+void cart_init()
+{
+	pg_data_t *pgdat;
+	struct zone *zone;
+	int i;
+
+	pgdat = pgdat_list;
+	
+	do {
+		for (i=0;i<MAX_NR_ZONES;++i) {
+			zone = &pgdat->node_zones[i];
+			
+			spin_lock_init(&zone->lru_lock);
+			INIT_LIST_HEAD(&zone->active_list);
+			INIT_LIST_HEAD(&zone->active_longterm);
+			INIT_LIST_HEAD(&zone->inactive_list);
+			
+			zone->nr_active = zone->nr_active_longterm = zone->nr_inactive = 0;
+			zone->nr_evicted_active = 0;
+			zone->nr_evicted_longterm = zone->present_pages - zone->pages_high;
+			
+			zone->cart_p = zone->cart_q = zone->nr_longterm = zone->nr_shortterm = 0;
+		}
+	} while ((pgdat = pgdat->pgdat_next));
+}
+
+/* The heart of the CART update function. This function is responsible for the movement of pages across the lists */	
+void update_cart_params(struct page *page)
+{
+	unsigned int rflags;
+	unsigned long evicted_active;
+	unsigned evicted_longterm;
+	struct zone *zone;
+
+	zone = page_zone(page);
+
+	rflags = recently_evicted(page->mapping, page->index);
+	evicted_active = (!rflags && !(rflags & NR_list));
+	evicted_longterm = (!rflags && (rflags & NR_list));
+	
+	if (evicted_active) {
+		zone->cart_p = min(zone->cart_p + max(zone->nr_shortterm/(zone->nr_evicted_active ?: 1UL), 1UL), (zone->present_pages - zone->pages_high));
+
+		++zone->nr_longterm;
+		SetLongTerm(page);
+		ClearPageReferenced(page);
+	}
+	else if (evicted_longterm) {
+		zone->cart_p = max(zone->cart_p - max(1UL, zone->nr_longterm/(zone->nr_evicted_longterm ?: 1UL)), 0UL);
+
+		++zone->nr_longterm;
+		ClearPageReferenced(page);
+
+		if (zone->nr_active_longterm + zone->nr_active + zone->nr_evicted_longterm - zone->nr_shortterm >=(zone->present_pages - zone->pages_high)) {
+			zone->cart_q = min(zone->cart_q + 1, 2*(zone->present_pages - zone->pages_high) - zone->nr_active);
+		}
+	}
+	else {
+		++zone->nr_shortterm;
+		ClearLongTerm(page);
+	}
+
+	add_page_to_active_list(zone, page);
+}
+
+/* The replace function. This function serches the active and longterm lists and looks for a candidate for replacement. This function selects the candidate and returns the corresponding structpage or returns NULL in case no page can be freed. The *where argument is used to indicate the parent list of the page so that, in case it cannot be written back, it can be placed back on the correct list */
+struct page *replace(struct zone *zone, unsigned int *where)
+{
+	struct list_head *list;
+	struct page *page = NULL;
+	int referenced = 0;
+	int debug_count=0;
+	unsigned int flags = 0, rflags;
+
+	list = &zone->active_longterm;
+	list = list->next;
+	while (list !=&zone->active_longterm) {
+		page = list_entry(list, struct page, lru);
+
+		if (!PageReferenced(page))
+			break;
+		
+		ClearPageReferenced(page);
+		del_page_from_active_longterm(zone, page);
+		add_page_to_active_tail(zone, page);
+		
+		if ((zone->nr_active_longterm + zone->nr_active + zone->nr_evicted_longterm - zone->nr_shortterm) >= (zone->present_pages - zone->pages_high))
+			zone->cart_q = min(zone->cart_q + 1, 2*(zone->present_pages - zone->pages_high) - zone->nr_active);
+
+		list = &zone->active_longterm;
+		list = list->next;
+		debug_count++;
+	}
+
+	debug_count=0;
+	list = &zone->active_list;
+	list = list->next;
+
+	while (list != &zone->active_list) {
+		page = list_entry(list, struct page, lru);
+		referenced = PageReferenced(page);
+		
+		if (!PageLongTerm(page) && !referenced)
+			break;
+			
+		ClearPageReferenced(page);
+		if (referenced) {
+			del_page_from_active(zone, page);
+			add_page_to_active_tail(zone, page);
+
+			if (zone->nr_active >= min(zone->cart_p+1, zone->nr_evicted_active) && !PageLongTerm(page)) {
+				SetLongTerm(page);
+				--zone->nr_shortterm;
+				++zone->nr_longterm;
+			}
+		}
+		else {
+			del_page_from_active(zone, page);
+			add_page_to_active_longterm_tail(zone, page);
+
+			zone->cart_q = max(zone->cart_q-1, (zone->present_pages - zone->pages_high) - zone->nr_active);
+		}
+
+		list = &zone->active_list;
+		list = list->next;
+		debug_count++;
+	}
+
+	page = NULL;
+	
+	if (zone->nr_active > max(1UL, zone->cart_p)) {
+		if (!list_empty(&zone->active_list)) {
+			page = list_entry(zone->active_list.next, struct page, lru);
+			del_page_from_active(zone, page);
+			--zone->nr_shortterm;
+        		++zone->nr_evicted_active;
+		}
+	}
+	else {
+		if (!list_empty(&zone->active_longterm)) {
+			page = list_entry(zone->active_longterm.next, struct page, lru);
+			del_page_from_active_longterm(zone, page);
+			--zone->nr_longterm;
+        		++zone->nr_evicted_longterm;
+			flags |= NR_list;
+		}
+	}
+
+	if (!page) return NULL;
+	*where = flags | NR_evict;
+	if (PageLongTerm(page)) flags |= NR_filter;
+
+	/* history replacement; always remember, if the page was already remembered
+	 * this will move it to the head.
+	 * Also assume |B1| + |B2| == c + 1, since |B1_j| + |B2_j| == c_j.
+	 */
+	if (zone->nr_evicted_active <= max(0UL, zone->cart_q)) flags |= NR_evict;
+
+	rflags = remember_page(page->mapping, page->index, flags);
+	if (rflags & NR_evict) {
+		if (likely(zone->nr_evicted_longterm)) --zone->nr_evicted_longterm;
+	} else {
+		if (likely(zone->nr_evicted_active)) --zone->nr_evicted_active;
+	}
+
+	return page;
+}
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/mm/nonresident.c linux-2.6.13-rc6-cart/mm/nonresident.c
--- linux-2.6.13-rc6/mm/nonresident.c	1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.13-rc6-cart/mm/nonresident.c	2005-08-15 21:46:17.000000000 +0200
@@ -0,0 +1,251 @@
+/*
+ * mm/nonresident.c
+ * (C) 2004,2005 Red Hat, Inc
+ * Written by Rik van Riel <riel@redhat.com>
+ * Released under the GPL, see the file COPYING for details.
+ * Adapted by Peter Zijlstra <a.p.zijlstra@chello.nl> for use by ARC
+ * like algorithms.
+ *
+ * Keeps track of whether a non-resident page was recently evicted
+ * and should be immediately promoted to the active list. This also
+ * helps automatically tune the inactive target.
+ *
+ * The pageout code stores a recently evicted page in this cache
+ * by calling remember_page(mapping/mm, index/vaddr)
+ * and can look it up in the cache by calling recently_evicted()
+ * with the same arguments.
+ *
+ * Note that there is no way to invalidate pages after eg. truncate
+ * or exit, we let the pages fall out of the non-resident set through
+ * normal replacement.
+ *
+ *
+ * Modified to work with ARC like algorithms who:
+ *  - need to balance two FIFOs; |b1| + |b2| = c,
+ *  - keep a flag per non-resident page.
+ *
+ * The bucket contains two single linked cyclic lists (CLOCKS) and each
+ * clock has a tail hand. By selecting a victim clock upon insertion it
+ * is possible to balance them.
+ *
+ * The slot looks like this:
+ * struct slot_t {
+ *         u32 cookie : 24; // LSB 
+ *         u32 index  :  6;
+ *         u32 filter :  1;
+ *         u32 clock  :  1; // MSB
+ * };
+ *
+ * The bucket is guarded by a spinlock.
+ */
+#include <linux/swap.h>
+#include <linux/mm.h>
+#include <linux/cache.h>
+#include <linux/spinlock.h>
+#include <linux/bootmem.h>
+#include <linux/hash.h>
+#include <linux/prefetch.h>
+#include <linux/kernel.h>
+
+#define TARGET_SLOTS	64
+#define NR_CACHELINES  (TARGET_SLOTS*sizeof(u32) / L1_CACHE_BYTES)
+#define NR_SLOTS	(((NR_CACHELINES * L1_CACHE_BYTES) - sizeof(spinlock_t) - 2*sizeof(u16)) / sizeof(u32))
+#if 0
+#if NR_SLOTS < (TARGET_SLOTS / 2)
+#warning very small slot size
+#if NR_SLOTS <= 0
+#error no room for slots left
+#endif
+#endif
+#endif
+
+#define BUILD_MASK(bits, shift) (((1 << (bits)) - 1) << (shift))
+
+#define FLAGS_BITS		2
+#define FLAGS_SHIFT		(sizeof(u32)*8 - FLAGS_BITS)
+#define FLAGS_MASK		BUILD_MASK(FLAGS_BITS, FLAGS_SHIFT)
+
+#define INDEX_BITS		6  /* ceil(log2(NR_SLOTS)) */
+#define INDEX_SHIFT		(FLAGS_SHIFT - INDEX_BITS)
+#define INDEX_MASK		BUILD_MASK(INDEX_BITS, INDEX_SHIFT)
+
+#define SET_INDEX(x, idx)	((x) = ((x) & ~INDEX_MASK) | ((idx) << INDEX_SHIFT))
+#define GET_INDEX(x)		(((x) & INDEX_MASK) >> INDEX_SHIFT)
+
+struct nr_bucket
+{
+	spinlock_t lock;
+	u16 hand[2];
+	u32 slot[NR_SLOTS];
+} ____cacheline_aligned;
+
+/* The non-resident page hash table. */
+static struct nr_bucket * nonres_table;
+static unsigned int nonres_shift;
+static unsigned int nonres_mask;
+
+/* hash the address into a bucket */
+static struct nr_bucket * nr_hash(void * mapping, unsigned long index)
+{
+	unsigned long bucket;
+	unsigned long hash;
+
+	hash = hash_ptr(mapping, BITS_PER_LONG);
+	hash = 37 * hash + hash_long(index, BITS_PER_LONG);
+	bucket = hash & nonres_mask;
+
+	return nonres_table + bucket;
+}
+
+/* hash the address, inode and flags into a cookie */
+/* the two msb are flags; where msb-1 is a type flag and msb a period flag */
+static u32 nr_cookie(struct address_space * mapping, unsigned long index, unsigned int flags)
+{
+	u32 c;
+	unsigned long cookie;
+	
+	cookie = hash_ptr(mapping, BITS_PER_LONG);
+	cookie = 37 * cookie + hash_long(index, BITS_PER_LONG);
+
+	if (mapping->host) {
+		cookie = 37 * cookie + hash_long(mapping->host->i_ino, BITS_PER_LONG);
+	}
+
+	c = (u32)(cookie >> (BITS_PER_LONG - 32));
+	c = (c & ~FLAGS_MASK) | ((flags << FLAGS_SHIFT) & FLAGS_MASK);
+	return c;
+}
+
+unsigned int recently_evicted(struct address_space * mapping, unsigned long index)
+{
+	struct nr_bucket * nr_bucket;
+	u32 wanted, mask;
+	unsigned int r_flags = 0;
+	int i;
+
+	prefetch(mapping->host);
+	nr_bucket = nr_hash(mapping, index);
+
+	spin_lock_prefetch(nr_bucket); // prefetch_range(nr_bucket, NR_CACHELINES);
+	wanted = nr_cookie(mapping, index, 0) & ~INDEX_MASK;
+	mask = ~(FLAGS_MASK | INDEX_MASK);
+
+	spin_lock(&nr_bucket->lock);
+	for (i = 0; i < NR_SLOTS; ++i) {
+		if ((nr_bucket->slot[i] & mask) == wanted) {
+			r_flags = nr_bucket->slot[i] >> FLAGS_SHIFT;
+			r_flags |= NR_evict; /* set the MSB to mark presence */
+			break;
+		}
+	}
+	spin_unlock(&nr_bucket->lock);
+
+	return r_flags;
+}
+
+/* flags: 
+ *   logical and of the page flags (NR_filter, NR_list) and
+ *   an NR_evict target
+ */
+u32 remember_page(struct address_space * mapping, unsigned long index, unsigned int flags)
+{
+	struct nr_bucket *nr_bucket;
+	u32 cookie;
+	u32 *slot, *tail;
+	unsigned int slot_pos, tail_pos;
+
+	prefetch(mapping->host);
+	nr_bucket = nr_hash(mapping, index);
+
+	spin_lock_prefetch(nr_bucket); // prefetchw_range(nr_bucket, NR_CACHELINES);
+	cookie = nr_cookie(mapping, index, flags);
+
+	flags &= NR_evict; /* removal chain */
+	spin_lock(&nr_bucket->lock);
+
+	/* free a slot */
+again:
+	tail_pos = nr_bucket->hand[!!flags];
+	BUG_ON(tail_pos >= NR_SLOTS);
+	tail = &nr_bucket->slot[tail_pos];
+	if (unlikely((*tail & NR_evict) != flags)) {
+		flags ^= NR_evict; /* empty chain; take other one */
+		goto again;
+	} 
+	BUG_ON((*tail & NR_evict) != flags);
+	/* free slot by swapping tail,tail+1, so that we skip over tail */
+	slot_pos = GET_INDEX(*tail);
+	BUG_ON(slot_pos >= NR_SLOTS);
+	slot = &nr_bucket->slot[slot_pos];
+	BUG_ON((*slot & NR_evict) != flags);
+	if (likely(tail != slot)) *slot = xchg(tail, *slot);
+	/* slot: -> [slot], old cookie */
+	BUG_ON(GET_INDEX(*slot) != slot_pos);
+
+	flags = (cookie & NR_evict); /* insertion chain */
+
+	/* place cookie in empty slot */
+	SET_INDEX(cookie, slot_pos); /* -> [slot], cookie */
+	cookie = xchg(slot, cookie); /* slot: -> [slot], cookie */
+
+	/* insert slot before tail; ie. MRU pos */
+	tail_pos = nr_bucket->hand[!!flags];
+	BUG_ON(tail_pos >= NR_SLOTS);
+	tail = &nr_bucket->slot[tail_pos];
+	if (likely((*tail & NR_evict) == flags && tail != slot))
+		*slot = xchg(tail, *slot); /* swap if not empty and not same */
+	nr_bucket->hand[!!flags] = slot_pos;
+
+	spin_unlock(&nr_bucket->lock);
+
+	return cookie;
+}
+
+/*
+ * For interactive workloads, we remember about as many non-resident pages
+ * as we have actual memory pages.  For server workloads with large inter-
+ * reference distances we could benefit from remembering more.
+ */
+static __initdata unsigned long nonresident_factor = 1;
+void __init init_nonresident(void)
+{
+	int target;
+	int i, j;
+
+	/*
+	 * Calculate the non-resident hash bucket target. Use a power of
+	 * two for the division because alloc_large_system_hash rounds up.
+	 */
+	target = nr_all_pages * nonresident_factor;
+	target /= (sizeof(struct nr_bucket) / sizeof(u32));
+
+	nonres_table = alloc_large_system_hash("Non-resident page tracking",
+					sizeof(struct nr_bucket),
+					target,
+					0,
+					HASH_EARLY | HASH_HIGHMEM,
+					&nonres_shift,
+					&nonres_mask,
+					0);
+
+	for (i = 0; i < (1 << nonres_shift); i++) {
+		spin_lock_init(&nonres_table[i].lock);
+		nonres_table[i].hand[0] = nonres_table[i].hand[1] = 0;
+		for (j = 0; j < NR_SLOTS; ++j) {
+			nonres_table[i].slot[j] = NR_evict;
+			if (j < NR_SLOTS - 1)
+				SET_INDEX(nonres_table[i].slot[j], j+1);
+			else /* j == NR_SLOTS - 1 */
+				SET_INDEX(nonres_table[i].slot[j], 0);
+		}
+	}
+}
+
+static int __init set_nonresident_factor(char * str)
+{
+	if (!str)
+		return 0;
+	nonresident_factor = simple_strtoul(str, &str, 0);
+	return 1;
+}
+__setup("nonresident_factor=", set_nonresident_factor);
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/mm/swap.c linux-2.6.13-rc6-cart/mm/swap.c
--- linux-2.6.13-rc6/mm/swap.c	2005-03-02 08:38:07.000000000 +0100
+++ linux-2.6.13-rc6-cart/mm/swap.c	2005-08-15 17:33:08.000000000 +0200
@@ -30,6 +30,7 @@
 #include <linux/cpu.h>
 #include <linux/notifier.h>
 #include <linux/init.h>
+#include <linux/cart.h>
 
 /* How many pages do we try to swap or page in/out together? */
 int page_cluster;
@@ -107,7 +108,7 @@ void fastcall activate_page(struct page 
 	if (PageLRU(page) && !PageActive(page)) {
 		del_page_from_inactive_list(zone, page);
 		SetPageActive(page);
-		add_page_to_active_list(zone, page);
+		update_cart_params(page);
 		inc_page_state(pgactivate);
 	}
 	spin_unlock_irq(&zone->lru_lock);
@@ -124,7 +125,6 @@ void fastcall mark_page_accessed(struct 
 {
 	if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
 		activate_page(page);
-		ClearPageReferenced(page);
 	} else if (!PageReferenced(page)) {
 		SetPageReferenced(page);
 	}
diff -NaurpX linux-2.6.13-rc6-cart/Documentation/dontdiff -x arch -x asm-um linux-2.6.13-rc6/mm/vmscan.c linux-2.6.13-rc6-cart/mm/vmscan.c
--- linux-2.6.13-rc6/mm/vmscan.c	2005-08-15 22:37:01.000000000 +0200
+++ linux-2.6.13-rc6-cart/mm/vmscan.c	2005-08-15 17:33:08.000000000 +0200
@@ -38,6 +38,7 @@
 #include <asm/div64.h>
 
 #include <linux/swapops.h>
+#include <linux/cart.h>
 
 /* possible outcome of pageout() */
 typedef enum {
@@ -555,6 +556,44 @@ keep:
 	return reclaimed;
 }
 
+/* This gets a page from the active_list and active_longterm lists in order to add to the incative list */
+static int get_from_active_lists(int nr_to_scan, struct zone *zone, struct list_head *dst, int *scanned)
+{
+	int nr_taken = 0;
+	struct page *page;
+	int scan = 0;
+	unsigned int flags;
+
+	while (scan++ < nr_to_scan) {
+		flags = 0;
+		page = replace(zone, &flags);
+
+		if (!page) break;
+		BUG_ON(!TestClearPageLRU(page));
+		BUG_ON(!flags);
+
+		if (get_page_testone(page)) {
+			/*
+			 * It is being freed elsewhere
+			 */
+			__put_page(page);
+			SetPageLRU(page);
+
+			if (!(flags & NR_list))
+				add_page_to_active_tail(zone, page);
+			else
+				add_page_to_active_longterm_tail(zone, page); 
+			continue;
+		} else {
+			list_add(&page->lru, dst);
+			nr_taken++;
+		}
+	}
+
+	*scanned = scan;
+	return nr_taken;
+}
+	
 /*
  * zone->lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
@@ -705,10 +744,10 @@ refill_inactive_zone(struct zone *zone, 
 
 	lru_add_drain();
 	spin_lock_irq(&zone->lru_lock);
-	pgmoved = isolate_lru_pages(nr_pages, &zone->active_list,
+	pgmoved = get_from_active_lists(nr_pages, zone,
 				    &l_hold, &pgscanned);
 	zone->pages_scanned += pgscanned;
-	zone->nr_active -= pgmoved;
+//	zone->nr_active -= pgmoved;
 	spin_unlock_irq(&zone->lru_lock);
 
 	/*