[Cyrill Gorcunov - Wed, Oct 22, 2008 at 08:53:54PM +0400]
| [Cyrill Gorcunov - Wed, Oct 22, 2008 at 08:35:30PM +0400]
| | [Christoph Lameter - Wed, Oct 22, 2008 at 09:28:14AM -0700]
| | > On Wed, 22 Oct 2008, Cyrill Gorcunov wrote:
| | >
| | >> Please check -- wouldn't it be better to use such a macro?
| | >
| | > Looks good. But could you rename OO_MAX to something different? There is
| | > already s->max which may cause confusion because s->max is the maximum
| | > number of objects in a slab. OO_MAX is the maximum mask?
| | >
| |
| | I supposed it would mean maximum object number inside page (ie quantity) which
| | is happen to be the same value as OO_MASK. Maybe OO_MAX_OBJ?
| |
| | - Cyrill -
|
| Btw Christoph fix me if I'm wrong but this 65535 is directly related to
| 16 bit shift. If we change the first value without changing the second we
| just break the SLUB I guess. I didn't read/understand SLUB code in details
| so could be wrong.
|
| - Cyrill -
Christoph how about this one?
- Cyrill -
---
mm/slub.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
Index: linux-2.6.git/mm/slub.c
===================================================================
--- linux-2.6.git.orig/mm/slub.c 2008-10-22 21:11:26.000000000 +0400
+++ linux-2.6.git/mm/slub.c 2008-10-22 21:19:12.000000000 +0400
@@ -153,6 +153,10 @@
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
#endif
+#define OO_SHIFT 16
+#define OO_MASK ((1 << OO_SHIFT) - 1)
+#define OO_MAX_OBJS 65535 /* see struct page.objects */
+
/* Internal SLUB flags */
#define __OBJECT_POISON 0x80000000 /* Poison object */
#define __SYSFS_ADD_DEFERRED 0x40000000 /* Not yet visible via sysfs */
@@ -290,7 +294,7 @@ static inline struct kmem_cache_order_ob
unsigned long size)
{
struct kmem_cache_order_objects x = {
- (order << 16) + (PAGE_SIZE << order) / size
+ (order << OO_SHIFT) + (PAGE_SIZE << order) / size
};
return x;
@@ -298,12 +302,12 @@ static inline struct kmem_cache_order_ob
static inline int oo_order(struct kmem_cache_order_objects x)
{
- return x.x >> 16;
+ return x.x >> OO_SHIFT;
}
static inline int oo_objects(struct kmem_cache_order_objects x)
{
- return x.x & ((1 << 16) - 1);
+ return x.x & OO_MASK;
}
#ifdef CONFIG_SLUB_DEBUG
@@ -764,8 +768,8 @@ static int on_freelist(struct kmem_cache
}
max_objects = (PAGE_SIZE << compound_order(page)) / s->size;
- if (max_objects > 65535)
- max_objects = 65535;
+ if (max_objects > OO_MAX_OBJS)
+ max_objects = OO_MAX_OBJS;
if (page->objects != max_objects) {
slab_err(s, page, "Wrong number of objects. Found %d but "
@@ -1819,8 +1823,8 @@ static inline int slab_order(int size, i
int rem;
int min_order = slub_min_order;
- if ((PAGE_SIZE << min_order) / size > 65535)
- return get_order(size * 65535) - 1;
+ if ((PAGE_SIZE << min_order) / size > OO_MAX_OBJS)
+ return get_order(size * OO_MAX_OBJS) - 1;
for (order = max(min_order,
fls(min_objects * size - 1) - PAGE_SHIFT);
--
