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authorHugh Dickins <hugh@veritas.com>2005-10-29 21:16:40 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-10-30 00:40:42 -0400
commit4c21e2f2441dc5fbb957b030333f5a3f2d02dea7 (patch)
tree1f76d33bb1d76221c6424bc5fed080a4f91349a6 /fs/jfs/jfs_metapage.c
parentb38c6845b695141259019e2b7c0fe6c32a6e720d (diff)
[PATCH] mm: split page table lock
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/jfs/jfs_metapage.c')
-rw-r--r--fs/jfs/jfs_metapage.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
index 26091a5f88d4..8a53981f9f27 100644
--- a/fs/jfs/jfs_metapage.c
+++ b/fs/jfs/jfs_metapage.c
@@ -86,7 +86,7 @@ struct meta_anchor {
86 atomic_t io_count; 86 atomic_t io_count;
87 struct metapage *mp[MPS_PER_PAGE]; 87 struct metapage *mp[MPS_PER_PAGE];
88}; 88};
89#define mp_anchor(page) ((struct meta_anchor *)page->private) 89#define mp_anchor(page) ((struct meta_anchor *)page_private(page))
90 90
91static inline struct metapage *page_to_mp(struct page *page, uint offset) 91static inline struct metapage *page_to_mp(struct page *page, uint offset)
92{ 92{
@@ -108,7 +108,7 @@ static inline int insert_metapage(struct page *page, struct metapage *mp)
108 if (!a) 108 if (!a)
109 return -ENOMEM; 109 return -ENOMEM;
110 memset(a, 0, sizeof(struct meta_anchor)); 110 memset(a, 0, sizeof(struct meta_anchor));
111 page->private = (unsigned long)a; 111 set_page_private(page, (unsigned long)a);
112 SetPagePrivate(page); 112 SetPagePrivate(page);
113 kmap(page); 113 kmap(page);
114 } 114 }
@@ -136,7 +136,7 @@ static inline void remove_metapage(struct page *page, struct metapage *mp)
136 a->mp[index] = NULL; 136 a->mp[index] = NULL;
137 if (--a->mp_count == 0) { 137 if (--a->mp_count == 0) {
138 kfree(a); 138 kfree(a);
139 page->private = 0; 139 set_page_private(page, 0);
140 ClearPagePrivate(page); 140 ClearPagePrivate(page);
141 kunmap(page); 141 kunmap(page);
142 } 142 }
@@ -156,13 +156,13 @@ static inline void dec_io(struct page *page, void (*handler) (struct page *))
156#else 156#else
157static inline struct metapage *page_to_mp(struct page *page, uint offset) 157static inline struct metapage *page_to_mp(struct page *page, uint offset)
158{ 158{
159 return PagePrivate(page) ? (struct metapage *)page->private : NULL; 159 return PagePrivate(page) ? (struct metapage *)page_private(page) : NULL;
160} 160}
161 161
162static inline int insert_metapage(struct page *page, struct metapage *mp) 162static inline int insert_metapage(struct page *page, struct metapage *mp)
163{ 163{
164 if (mp) { 164 if (mp) {
165 page->private = (unsigned long)mp; 165 set_page_private(page, (unsigned long)mp);
166 SetPagePrivate(page); 166 SetPagePrivate(page);
167 kmap(page); 167 kmap(page);
168 } 168 }
@@ -171,7 +171,7 @@ static inline int insert_metapage(struct page *page, struct metapage *mp)
171 171
172static inline void remove_metapage(struct page *page, struct metapage *mp) 172static inline void remove_metapage(struct page *page, struct metapage *mp)
173{ 173{
174 page->private = 0; 174 set_page_private(page, 0);
175 ClearPagePrivate(page); 175 ClearPagePrivate(page);
176 kunmap(page); 176 kunmap(page);
177} 177}