For this reason I think it's a good idea to make page_cache_size an `int'
so avoiding not necessary and not scalable SMP lock on the bus.
Here a patch against 2.3.11-pre6 (I checked it compiles).
diff -urN 2.3.11-pre6/fs/proc/array.c tmp/fs/proc/array.c
--- 2.3.11-pre6/fs/proc/array.c Tue Jul 20 18:37:45 1999
+++ tmp/fs/proc/array.c Wed Jul 21 02:14:53 1999
@@ -348,7 +348,7 @@
len = sprintf(buffer, " total: used: free: shared: buffers: cached:\n"
"Mem: %8lu %8lu %8lu %8lu %8lu %8lu\n"
"Swap: %8lu %8lu %8lu\n",
- i.totalram, i.totalram-i.freeram, i.freeram, i.sharedram, i.bufferram, atomic_read(&page_cache_size)*PAGE_SIZE,
+ i.totalram, i.totalram-i.freeram, i.freeram, i.sharedram, i.bufferram, page_cache_size*PAGE_SIZE,
i.totalswap, i.totalswap-i.freeswap, i.freeswap);
/*
* Tagged format, for easy grepping and expansion. The above will go away
@@ -366,7 +366,7 @@
i.freeram >> 10,
i.sharedram >> 10,
i.bufferram >> 10,
- atomic_read(&page_cache_size) << (PAGE_SHIFT - 10),
+ page_cache_size << (PAGE_SHIFT - 10),
i.totalswap >> 10,
i.freeswap >> 10);
}
diff -urN 2.3.11-pre6/include/linux/mm.h tmp/include/linux/mm.h
--- 2.3.11-pre6/include/linux/mm.h Tue Jul 20 18:47:12 1999
+++ tmp/include/linux/mm.h Wed Jul 21 02:15:10 1999
@@ -414,7 +414,7 @@
#define buffer_under_min() ((atomic_read(&buffermem) >> PAGE_SHIFT) * 100 < \
buffer_mem.min_percent * num_physpages)
-#define pgcache_under_min() (atomic_read(&page_cache_size) * 100 < \
+#define pgcache_under_min() (page_cache_size * 100 < \
page_cache.min_percent * num_physpages)
#endif /* __KERNEL__ */
diff -urN 2.3.11-pre6/include/linux/pagemap.h tmp/include/linux/pagemap.h
--- 2.3.11-pre6/include/linux/pagemap.h Tue Jul 20 18:47:12 1999
+++ tmp/include/linux/pagemap.h Wed Jul 21 02:21:31 1999
@@ -43,7 +43,7 @@
#define PAGE_HASH_BITS (page_hash_bits)
#define PAGE_HASH_SIZE (1 << PAGE_HASH_BITS)
-extern atomic_t page_cache_size; /* # of pages currently in the hash table */
+extern int page_cache_size; /* # of pages currently in the hash table */
extern struct page **page_hash_table;
extern void page_cache_init(unsigned long);
diff -urN 2.3.11-pre6/include/linux/swap.h tmp/include/linux/swap.h
--- 2.3.11-pre6/include/linux/swap.h Tue Jul 20 18:47:12 1999
+++ tmp/include/linux/swap.h Wed Jul 21 02:21:13 1999
@@ -66,7 +66,6 @@
extern int nr_free_pages;
extern atomic_t nr_async_pages;
extern struct inode swapper_inode;
-extern atomic_t page_cache_size;
extern atomic_t buffermem;
/* Incomplete types for prototype declarations: */
diff -urN 2.3.11-pre6/mm/filemap.c tmp/mm/filemap.c
--- 2.3.11-pre6/mm/filemap.c Tue Jul 20 18:37:45 1999
+++ tmp/mm/filemap.c Wed Jul 21 02:17:05 1999
@@ -35,7 +35,7 @@
* page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
*/
-atomic_t page_cache_size = ATOMIC_INIT(0);
+int page_cache_size;
unsigned int page_hash_bits;
struct page **page_hash_table;
@@ -44,7 +44,7 @@
void __add_page_to_hash_queue(struct page * page, struct page **p)
{
- atomic_inc(&page_cache_size);
+ page_cache_size++; /* serialized by the pagecache_lock */
if((page->next_hash = *p) != NULL)
(*p)->pprev_hash = &page->next_hash;
*p = page;
@@ -61,7 +61,7 @@
*page->pprev_hash = page->next_hash;
page->pprev_hash = NULL;
}
- atomic_dec(&page_cache_size);
+ page_cache_size--; /* serialized by the pagecache_lock */
}
static void remove_page_from_inode_queue(struct page * page)
diff -urN 2.3.11-pre6/mm/mmap.c tmp/mm/mmap.c
--- 2.3.11-pre6/mm/mmap.c Tue Jul 13 02:02:40 1999
+++ tmp/mm/mmap.c Wed Jul 21 02:17:20 1999
@@ -63,7 +63,7 @@
return 1;
free = atomic_read(&buffermem) >> PAGE_SHIFT;
- free += atomic_read(&page_cache_size);
+ free += page_cache_size;
free += nr_free_pages;
free += nr_swap_pages;
free -= (page_cache.min_percent + buffer_mem.min_percent + 2)*num_physpages/100;
Andrea
-
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