From 481b4bb5e370aa69c1dc276bd08871ec01b41d2a Mon Sep 17 00:00:00 2001 From: Richard Kennedy Date: Tue, 22 Mar 2011 16:32:50 -0700 Subject: mm: mm_struct: remove 16 bytes of alignment padding on 64 bit builds 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm_types.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 26bc4e2cd275..02aa5619709b 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. */ -- cgit v1.2.3