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mm: convert mm->cpu_vm_cpumask into cpumask_var_t

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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 <kosaki.motohiro@jp.fujitsu.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro
2011-05-24 17:12:15 -07:00
committed by Linus Torvalds
parent 692e0b3542
commit de03c72cfc
7 changed files with 44 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

37
kernel/fork.c
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@ -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()