From de03c72cfce5b263a674d04348b58475ec50163c Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Tue, 24 May 2011 17:12:15 -0700 Subject: [PATCH] mm: convert mm->cpu_vm_cpumask into cpumask_var_t cpumask_t is very big struct and cpu_vm_mask is placed wrong position. It might lead to reduce cache hit ratio. This patch has two change. 1) Move the place of cpumask into last of mm_struct. Because usually cpumask is accessed only front bits when the system has cpu-hotplug capability 2) Convert cpu_vm_mask into cpumask_var_t. It may help to reduce memory footprint if cpumask_size() will use nr_cpumask_bits properly in future. In addition, this patch change the name of cpu_vm_mask with cpu_vm_mask_var. It may help to detect out of tree cpu_vm_mask users. This patch has no functional change. [akpm@linux-foundation.org: build fix] [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: KOSAKI Motohiro Cc: David Howells Cc: Koichi Yasutake Cc: Hugh Dickins Cc: Chris Metcalf Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/cachetlb.txt | 2 +- arch/x86/kernel/tboot.c | 1 - include/linux/mm_types.h | 9 ++++++--- include/linux/sched.h | 1 + init/main.c | 2 ++ kernel/fork.c | 37 ++++++++++++++++++++++++++++++++++--- mm/init-mm.c | 1 - 7 files changed, 44 insertions(+), 9 deletions(-) diff --git a/Documentation/cachetlb.txt b/Documentation/cachetlb.txt index 9164ae3b83bc..9b728dc17535 100644 --- a/Documentation/cachetlb.txt +++ b/Documentation/cachetlb.txt @@ -16,7 +16,7 @@ on all processors in the system. Don't let this scare you into thinking SMP cache/tlb flushing must be so inefficient, this is in fact an area where many optimizations are possible. For example, if it can be proven that a user address space has never executed -on a cpu (see vma->cpu_vm_mask), one need not perform a flush +on a cpu (see mm_cpumask()), one need not perform a flush for this address space on that cpu. First, the TLB flushing interfaces, since they are the simplest. The diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c index 998e972f3b1a..30ac65df7d4e 100644 --- a/arch/x86/kernel/tboot.c +++ b/arch/x86/kernel/tboot.c @@ -110,7 +110,6 @@ static struct mm_struct tboot_mm = { .mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem), .page_table_lock = __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock), .mmlist = LIST_HEAD_INIT(init_mm.mmlist), - .cpu_vm_mask = CPU_MASK_ALL, }; static inline void switch_to_tboot_pt(void) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 201998e5b530..c2f9ea7922f4 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -265,8 +265,6 @@ struct mm_struct { struct linux_binfmt *binfmt; - cpumask_t cpu_vm_mask; - /* Architecture-specific MM context */ mm_context_t context; @@ -316,9 +314,14 @@ struct mm_struct { #ifdef CONFIG_TRANSPARENT_HUGEPAGE pgtable_t pmd_huge_pte; /* protected by page_table_lock */ #endif + + cpumask_var_t cpu_vm_mask_var; }; /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */ -#define mm_cpumask(mm) (&(mm)->cpu_vm_mask) +static inline cpumask_t *mm_cpumask(struct mm_struct *mm) +{ + return mm->cpu_vm_mask_var; +} #endif /* _LINUX_MM_TYPES_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 44b8faaac7c0..f18300eddfcb 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2176,6 +2176,7 @@ static inline void mmdrop(struct mm_struct * mm) if (unlikely(atomic_dec_and_test(&mm->mm_count))) __mmdrop(mm); } +extern int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm); /* mmput gets rid of the mappings and all user-space */ extern void mmput(struct mm_struct *); diff --git a/init/main.c b/init/main.c index 48df882d51d2..22da33918aef 100644 --- a/init/main.c +++ b/init/main.c @@ -509,6 +509,8 @@ asmlinkage void __init start_kernel(void) sort_main_extable(); trap_init(); mm_init(); + BUG_ON(mm_init_cpumask(&init_mm, 0)); + /* * Set up the scheduler prior starting any interrupts (such as the * timer interrupt). Full topology setup happens at smp_init() diff --git a/kernel/fork.c b/kernel/fork.c index 927692734bcf..8e7e135d0817 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -485,6 +485,20 @@ static void mm_init_aio(struct mm_struct *mm) #endif } +int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm) +{ +#ifdef CONFIG_CPUMASK_OFFSTACK + if (!alloc_cpumask_var(&mm->cpu_vm_mask_var, GFP_KERNEL)) + return -ENOMEM; + + if (oldmm) + cpumask_copy(mm_cpumask(mm), mm_cpumask(oldmm)); + else + memset(mm_cpumask(mm), 0, cpumask_size()); +#endif + return 0; +} + static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p) { atomic_set(&mm->mm_users, 1); @@ -521,10 +535,20 @@ struct mm_struct * mm_alloc(void) struct mm_struct * mm; mm = allocate_mm(); - if (mm) { - memset(mm, 0, sizeof(*mm)); - mm = mm_init(mm, current); + if (!mm) + return NULL; + + memset(mm, 0, sizeof(*mm)); + mm = mm_init(mm, current); + if (!mm) + return NULL; + + if (mm_init_cpumask(mm, NULL)) { + mm_free_pgd(mm); + free_mm(mm); + return NULL; } + return mm; } @@ -536,6 +560,7 @@ struct mm_struct * mm_alloc(void) void __mmdrop(struct mm_struct *mm) { BUG_ON(mm == &init_mm); + free_cpumask_var(mm->cpu_vm_mask_var); mm_free_pgd(mm); destroy_context(mm); mmu_notifier_mm_destroy(mm); @@ -690,6 +715,9 @@ struct mm_struct *dup_mm(struct task_struct *tsk) if (!mm_init(mm, tsk)) goto fail_nomem; + if (mm_init_cpumask(mm, oldmm)) + goto fail_nocpumask; + if (init_new_context(tsk, mm)) goto fail_nocontext; @@ -716,6 +744,9 @@ fail_nomem: return NULL; fail_nocontext: + free_cpumask_var(mm->cpu_vm_mask_var); + +fail_nocpumask: /* * If init_new_context() failed, we cannot use mmput() to free the mm * because it calls destroy_context() diff --git a/mm/init-mm.c b/mm/init-mm.c index 1d29cdfe8ebb..4019979b2637 100644 --- a/mm/init-mm.c +++ b/mm/init-mm.c @@ -21,6 +21,5 @@ struct mm_struct init_mm = { .mmap_sem = __RWSEM_INITIALIZER(init_mm.mmap_sem), .page_table_lock = __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock), .mmlist = LIST_HEAD_INIT(init_mm.mmlist), - .cpu_vm_mask = CPU_MASK_ALL, INIT_MM_CONTEXT(init_mm) }; -- 2.34.1