The patch titled
mm: mm_struct remove 16 bytes of alignment padding on 64 bit builds
has been added to the -mm tree. Its filename is
mm-mm_struct-remove-16-bytes-of-alignment-padding-on-64-bit-builds.patch
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------------------------------------------------------
Subject: mm: mm_struct remove 16 bytes of alignment padding on 64 bit builds
From: Richard Kennedy <richard@xxxxxxxxxxxxxxx>
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>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/mm_types.h | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff -puN include/linux/mm_types.h~mm-mm_struct-remove-16-bytes-of-alignment-padding-on-64-bit-builds include/linux/mm_types.h
--- a/include/linux/mm_types.h~mm-mm_struct-remove-16-bytes-of-alignment-padding-on-64-bit-builds
+++ a/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. */
_
Patches currently in -mm which might be from richard@xxxxxxxxxxxxxxx are
mm-mm_struct-remove-16-bytes-of-alignment-padding-on-64-bit-builds.patch
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