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Subject[PATCH 04/14] Conversion of nr_pagecache to per zone counter
Conversion of nr_pagecache to a per zone counter

Currently a single atomic variable is used to establish the size of the page
cache in the whole machine. The zoned VM counters have the same method of
implementation as the nr_pagecache code but also allow the determination
of the pagecache size per zone.

Remove the special implementation for nr_pagecache and make it a zoned
counter.

Updates of the page cache counters are always performed with interrupts off.
We can therefore use the __ variant here.

This will make UP no longer require atomic operations for nr_pagecache.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.17-rc6-mm1/include/linux/pagemap.h
===================================================================
--- linux-2.6.17-rc6-mm1.orig/include/linux/pagemap.h 2006-06-08 13:03:39.304520730 -0700
+++ linux-2.6.17-rc6-mm1/include/linux/pagemap.h 2006-06-08 14:07:35.879548728 -0700
@@ -115,51 +115,6 @@ int add_to_page_cache_lru(struct page *p
extern void remove_from_page_cache(struct page *page);
extern void __remove_from_page_cache(struct page *page);

-extern atomic_t nr_pagecache;
-
-#ifdef CONFIG_SMP
-
-#define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2)
-DECLARE_PER_CPU(long, nr_pagecache_local);
-
-/*
- * pagecache_acct implements approximate accounting for pagecache.
- * vm_enough_memory() do not need high accuracy. Writers will keep
- * an offset in their per-cpu arena and will spill that into the
- * global count whenever the absolute value of the local count
- * exceeds the counter's threshold.
- *
- * MUST be protected from preemption.
- * current protection is mapping->page_lock.
- */
-static inline void pagecache_acct(int count)
-{
- long *local;
-
- local = &__get_cpu_var(nr_pagecache_local);
- *local += count;
- if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) {
- atomic_add(*local, &nr_pagecache);
- *local = 0;
- }
-}
-
-#else
-
-static inline void pagecache_acct(int count)
-{
- atomic_add(count, &nr_pagecache);
-}
-#endif
-
-static inline unsigned long get_page_cache_size(void)
-{
- int ret = atomic_read(&nr_pagecache);
- if (unlikely(ret < 0))
- ret = 0;
- return ret;
-}
-
/*
* Return byte-offset into filesystem object for page.
*/
Index: linux-2.6.17-rc6-mm1/mm/swap_state.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/mm/swap_state.c 2006-06-08 13:03:39.924599579 -0700
+++ linux-2.6.17-rc6-mm1/mm/swap_state.c 2006-06-08 14:07:35.880525230 -0700
@@ -89,7 +89,7 @@ static int __add_to_swap_cache(struct pa
SetPageSwapCache(page);
set_page_private(page, entry.val);
total_swapcache_pages++;
- pagecache_acct(1);
+ __inc_zone_page_state(page, NR_PAGECACHE);
}
write_unlock_irq(&swapper_space.tree_lock);
radix_tree_preload_end();
@@ -135,7 +135,7 @@ void __delete_from_swap_cache(struct pag
set_page_private(page, 0);
ClearPageSwapCache(page);
total_swapcache_pages--;
- pagecache_acct(-1);
+ __dec_zone_page_state(page, NR_PAGECACHE);
INC_CACHE_INFO(del_total);
}

Index: linux-2.6.17-rc6-mm1/mm/filemap.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/mm/filemap.c 2006-06-08 13:03:39.864056448 -0700
+++ linux-2.6.17-rc6-mm1/mm/filemap.c 2006-06-08 14:07:35.881501732 -0700
@@ -126,7 +126,7 @@ void __remove_from_page_cache(struct pag
radix_tree_delete(&mapping->page_tree, page->index);
page->mapping = NULL;
mapping->nrpages--;
- pagecache_acct(-1);
+ __dec_zone_page_state(page, NR_PAGECACHE);
}
EXPORT_SYMBOL(__remove_from_page_cache);

@@ -424,7 +424,7 @@ int add_to_page_cache(struct page *page,
page->mapping = mapping;
page->index = offset;
mapping->nrpages++;
- pagecache_acct(1);
+ __inc_zone_page_state(page, NR_PAGECACHE);
}
write_unlock_irq(&mapping->tree_lock);
radix_tree_preload_end();
Index: linux-2.6.17-rc6-mm1/mm/page_alloc.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/mm/page_alloc.c 2006-06-08 13:55:23.119232821 -0700
+++ linux-2.6.17-rc6-mm1/mm/page_alloc.c 2006-06-08 14:07:35.883454737 -0700
@@ -1583,12 +1583,6 @@ static void show_node(struct zone *zone)
*/
static DEFINE_PER_CPU(struct page_state, page_states) = {0};

-atomic_t nr_pagecache = ATOMIC_INIT(0);
-EXPORT_SYMBOL(nr_pagecache);
-#ifdef CONFIG_SMP
-DEFINE_PER_CPU(long, nr_pagecache_local) = 0;
-#endif
-
static void __get_page_state(struct page_state *ret, int nr, cpumask_t *cpumask)
{
unsigned cpu;
@@ -2802,6 +2796,7 @@ struct seq_operations zoneinfo_op = {
static char *vmstat_text[] = {
/* Zoned VM counters */
"nr_mapped",
+ "nr_pagecache",

/* Page state */
"nr_dirty",
Index: linux-2.6.17-rc6-mm1/mm/mmap.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/mm/mmap.c 2006-06-08 13:03:39.900187026 -0700
+++ linux-2.6.17-rc6-mm1/mm/mmap.c 2006-06-08 14:07:35.884431239 -0700
@@ -96,7 +96,7 @@ int __vm_enough_memory(long pages, int c
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
unsigned long n;

- free = get_page_cache_size();
+ free = global_page_state(NR_PAGECACHE);
free += nr_swap_pages;

/*
Index: linux-2.6.17-rc6-mm1/mm/nommu.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/mm/nommu.c 2006-06-05 17:57:02.000000000 -0700
+++ linux-2.6.17-rc6-mm1/mm/nommu.c 2006-06-08 14:07:36.292609102 -0700
@@ -1122,7 +1122,7 @@ int __vm_enough_memory(long pages, int c
if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
unsigned long n;

- free = get_page_cache_size();
+ free = global_page_state(NR_PAGECACHE);
free += nr_swap_pages;

/*
Index: linux-2.6.17-rc6-mm1/arch/sparc64/kernel/sys_sunos32.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/arch/sparc64/kernel/sys_sunos32.c 2006-06-08 13:03:31.354816936 -0700
+++ linux-2.6.17-rc6-mm1/arch/sparc64/kernel/sys_sunos32.c 2006-06-08 14:07:36.469355975 -0700
@@ -155,7 +155,7 @@ asmlinkage int sunos_brk(u32 baddr)
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
- freepages = get_page_cache_size();
+ freepages = global_page_state(NR_PAGECACHE);
freepages >>= 1;
freepages += nr_free_pages();
freepages += nr_swap_pages;
Index: linux-2.6.17-rc6-mm1/arch/sparc/kernel/sys_sunos.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/arch/sparc/kernel/sys_sunos.c 2006-06-08 13:03:31.362628953 -0700
+++ linux-2.6.17-rc6-mm1/arch/sparc/kernel/sys_sunos.c 2006-06-08 14:07:36.481074000 -0700
@@ -196,7 +196,7 @@ asmlinkage int sunos_brk(unsigned long b
* simple, it hopefully works in most obvious cases.. Easy to
* fool it, but this should catch most mistakes.
*/
- freepages = get_page_cache_size();
+ freepages = global_page_state(NR_PAGECACHE);
freepages >>= 1;
freepages += nr_free_pages();
freepages += nr_swap_pages;
Index: linux-2.6.17-rc6-mm1/fs/proc/proc_misc.c
===================================================================
--- linux-2.6.17-rc6-mm1.orig/fs/proc/proc_misc.c 2006-06-08 13:55:23.115326813 -0700
+++ linux-2.6.17-rc6-mm1/fs/proc/proc_misc.c 2006-06-08 14:07:36.482050502 -0700
@@ -142,7 +142,7 @@ static int meminfo_read_proc(char *page,
allowed = ((totalram_pages - hugetlb_total_pages())
* sysctl_overcommit_ratio / 100) + total_swap_pages;

- cached = get_page_cache_size() - total_swapcache_pages - i.bufferram;
+ cached = global_page_state(NR_PAGECACHE) - total_swapcache_pages - i.bufferram;
if (cached < 0)
cached = 0;

Index: linux-2.6.17-rc6-mm1/include/linux/mmzone.h
===================================================================
--- linux-2.6.17-rc6-mm1.orig/include/linux/mmzone.h 2006-06-08 13:55:23.121185825 -0700
+++ linux-2.6.17-rc6-mm1/include/linux/mmzone.h 2006-06-08 14:07:36.482050502 -0700
@@ -49,7 +49,7 @@ struct zone_padding {
enum zone_stat_item {
NR_MAPPED, /* mapped into pagetables.
only modified from process context */
-
+ NR_PAGECACHE, /* file backed pages */
NR_STAT_ITEMS };

#ifdef CONFIG_SMP
-
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