From b962716b459505a8d83aea313fea0abe76749f42 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hugh@veritas.com>
Date: Tue, 6 Jan 2009 14:39:41 -0800
Subject: mm: optimize get_scan_ratio for no swap
Rik suggests a simplified get_scan_ratio() for !CONFIG_SWAP. Yes, the gcc
optimizer gives us that, when nr_swap_pages is #defined as 0L. Move usual
declaration to swapfile.c: it never belonged in page_alloc.c.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
include/linux/swap.h | 5 +++--
mm/page_alloc.c | 1 -
mm/swapfile.c | 1 +
mm/vmscan.c | 12 ++++++------
4 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index c0d23ac710d5..3a31cc25bd2c 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -163,7 +163,6 @@ struct swap_list_t {
/* linux/mm/page_alloc.c */
extern unsigned long totalram_pages;
extern unsigned long totalreserve_pages;
-extern long nr_swap_pages;
extern unsigned int nr_free_buffer_pages(void);
extern unsigned int nr_free_pagecache_pages(void);
@@ -291,6 +290,7 @@ extern struct page *swapin_readahead(swp_entry_t, gfp_t,
struct vm_area_struct *vma, unsigned long addr);
/* linux/mm/swapfile.c */
+extern long nr_swap_pages;
extern long total_swap_pages;
extern void si_swapinfo(struct sysinfo *);
extern swp_entry_t get_swap_page(void);
@@ -331,7 +331,8 @@ static inline void disable_swap_token(void)
#else /* CONFIG_SWAP */
-#define total_swap_pages 0
+#define nr_swap_pages 0L
+#define total_swap_pages 0L
#define total_swapcache_pages 0UL
#define si_swapinfo(val) \
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ce2a026219bc..65133436fe3d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -69,7 +69,6 @@ EXPORT_SYMBOL(node_states);
unsigned long totalram_pages __read_mostly;
unsigned long totalreserve_pages __read_mostly;
-long nr_swap_pages;
int percpu_pagelist_fraction;
#ifdef CONFIG_HUGETLB_PAGE_SIZE_VARIABLE
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 9ce7f81c8abc..725e56c362de 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -35,6 +35,7 @@
static DEFINE_SPINLOCK(swap_lock);
static unsigned int nr_swapfiles;
+long nr_swap_pages;
long total_swap_pages;
static int swap_overflow;
static int least_priority;
diff --git a/mm/vmscan.c b/mm/vmscan.c
index f350523a8eee..d500b906746c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1327,12 +1327,6 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
unsigned long anon_prio, file_prio;
unsigned long ap, fp;
- anon = zone_page_state(zone, NR_ACTIVE_ANON) +
- zone_page_state(zone, NR_INACTIVE_ANON);
- file = zone_page_state(zone, NR_ACTIVE_FILE) +
- zone_page_state(zone, NR_INACTIVE_FILE);
- free = zone_page_state(zone, NR_FREE_PAGES);
-
/* If we have no swap space, do not bother scanning anon pages. */
if (nr_swap_pages <= 0) {
percent[0] = 0;
@@ -1340,6 +1334,12 @@ static void get_scan_ratio(struct zone *zone, struct scan_control *sc,
return;
}
+ anon = zone_page_state(zone, NR_ACTIVE_ANON) +
+ zone_page_state(zone, NR_INACTIVE_ANON);
+ file = zone_page_state(zone, NR_ACTIVE_FILE) +
+ zone_page_state(zone, NR_INACTIVE_FILE);
+ free = zone_page_state(zone, NR_FREE_PAGES);
+
/* If we have very few page cache pages, force-scan anon pages. */
if (unlikely(file + free <= zone->pages_high)) {
percent[0] = 100;
--
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