Reorder mm_struct to remove 16 bytes of alignment padding on 64 bit
builds.
On my config this shrinks mm_struct by enough to fit in one fewer cache
lines and allows more objects per slab in mm_struct kmem_cache under
SLUB.
slabinfo before patch :-
Sizes (bytes) Slabs
--------------------------------
Object : 848 Total : 9
SlabObj: 896 Full : 2
SlabSiz: 16384 Partial: 5
Loss : 48 CpuSlab: 2
Align : 64 Objects: 18
slabinfo after :-
Sizes (bytes) Slabs
--------------------------------
Object : 832 Total : 7
SlabObj: 832 Full : 2
SlabSiz: 16384 Partial: 3
Loss : 0 CpuSlab: 2
Align : 64 Objects: 19
Signed-off-by: Richard Kennedy <richard@xxxxxxxxxxxxxxx>
---
patch against v2.6.38-rc4
compiled & tested on x86_64
regards
Richard
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 26bc4e2..02aa561 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -237,8 +237,9 @@ struct mm_struct {
atomic_t mm_users; /* How many users with user space? */
atomic_t mm_count; /* How many references to "struct mm_struct" (users count as 1) */
int map_count; /* number of VMAs */
- struct rw_semaphore mmap_sem;
+
spinlock_t page_table_lock; /* Protects page tables and some counters */
+ struct rw_semaphore mmap_sem;
struct list_head mmlist; /* List of maybe swapped mm's. These are globally strung
* together off init_mm.mmlist, and are protected
@@ -281,6 +282,9 @@ struct mm_struct {
unsigned int token_priority;
unsigned int last_interval;
+ /* How many tasks sharing this mm are OOM_DISABLE */
+ atomic_t oom_disable_count;
+
unsigned long flags; /* Must use atomic bitops to access the bits */
struct core_state *core_state; /* coredumping support */
@@ -313,8 +317,6 @@ struct mm_struct {
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
- /* How many tasks sharing this mm are OOM_DISABLE */
- atomic_t oom_disable_count;
};
/* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>