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Message-Id: <1302847688-8076-1-git-send-email-namhyung@gmail.com>
Date: Fri, 15 Apr 2011 15:08:08 +0900
From: Namhyung Kim <namhyung@...il.com>
To: Minchan Kim <minchan.kim@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2] mempolicy: reduce references to the current
Remove duplicated reference to the 'current' task using a local
variable. Since refering the current can be a burden, it'd better
cache the reference, IMHO. At least this saves some bytes on x86_64.
$ size mempolicy-{old,new}.o
text data bss dec hex filename
25203 2448 9176 36827 8fdb mempolicy-old.o
25136 2448 9184 36768 8fa0 mempolicy-new.o
Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
mm/mempolicy.c | 58 +++++++++++++++++++++++++++++--------------------------
1 files changed, 31 insertions(+), 27 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 959a8b8c7350..5a30065590aa 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -304,6 +304,7 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
enum mpol_rebind_step step)
{
nodemask_t tmp;
+ struct task_struct *tsk = current;
if (pol->flags & MPOL_F_STATIC_NODES)
nodes_and(tmp, pol->w.user_nodemask, *nodes);
@@ -335,12 +336,12 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
else
BUG();
- if (!node_isset(current->il_next, tmp)) {
- current->il_next = next_node(current->il_next, tmp);
- if (current->il_next >= MAX_NUMNODES)
- current->il_next = first_node(tmp);
- if (current->il_next >= MAX_NUMNODES)
- current->il_next = numa_node_id();
+ if (!node_isset(tsk->il_next, tmp)) {
+ tsk->il_next = next_node(tsk->il_next, tmp);
+ if (tsk->il_next >= MAX_NUMNODES)
+ tsk->il_next = first_node(tmp);
+ if (tsk->il_next >= MAX_NUMNODES)
+ tsk->il_next = numa_node_id();
}
}
@@ -714,7 +715,8 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
nodemask_t *nodes)
{
struct mempolicy *new, *old;
- struct mm_struct *mm = current->mm;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
NODEMASK_SCRATCH(scratch);
int ret;
@@ -734,22 +736,22 @@ static long do_set_mempolicy(unsigned short mode, unsigned short flags,
*/
if (mm)
down_write(&mm->mmap_sem);
- task_lock(current);
+ task_lock(tsk);
ret = mpol_set_nodemask(new, nodes, scratch);
if (ret) {
- task_unlock(current);
+ task_unlock(tsk);
if (mm)
up_write(&mm->mmap_sem);
mpol_put(new);
goto out;
}
- old = current->mempolicy;
- current->mempolicy = new;
+ old = tsk->mempolicy;
+ tsk->mempolicy = new;
mpol_set_task_struct_flag();
if (new && new->mode == MPOL_INTERLEAVE &&
nodes_weight(new->v.nodes))
- current->il_next = first_node(new->v.nodes);
- task_unlock(current);
+ tsk->il_next = first_node(new->v.nodes);
+ task_unlock(tsk);
if (mm)
up_write(&mm->mmap_sem);
@@ -805,9 +807,10 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
unsigned long addr, unsigned long flags)
{
int err;
- struct mm_struct *mm = current->mm;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
struct vm_area_struct *vma = NULL;
- struct mempolicy *pol = current->mempolicy;
+ struct mempolicy *pol = tsk->mempolicy;
if (flags &
~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR|MPOL_F_MEMS_ALLOWED))
@@ -817,9 +820,9 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
if (flags & (MPOL_F_NODE|MPOL_F_ADDR))
return -EINVAL;
*policy = 0; /* just so it's initialized */
- task_lock(current);
+ task_lock(tsk);
*nmask = cpuset_current_mems_allowed;
- task_unlock(current);
+ task_unlock(tsk);
return 0;
}
@@ -851,9 +854,9 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
if (err < 0)
goto out;
*policy = err;
- } else if (pol == current->mempolicy &&
+ } else if (pol == tsk->mempolicy &&
pol->mode == MPOL_INTERLEAVE) {
- *policy = current->il_next;
+ *policy = tsk->il_next;
} else {
err = -EINVAL;
goto out;
@@ -869,7 +872,7 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
}
if (vma) {
- up_read(¤t->mm->mmap_sem);
+ up_read(&mm->mmap_sem);
vma = NULL;
}
@@ -878,16 +881,16 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
if (mpol_store_user_nodemask(pol)) {
*nmask = pol->w.user_nodemask;
} else {
- task_lock(current);
+ task_lock(tsk);
get_policy_nodemask(pol, nmask);
- task_unlock(current);
+ task_unlock(tsk);
}
}
out:
mpol_cond_put(pol);
if (vma)
- up_read(¤t->mm->mmap_sem);
+ up_read(&mm->mmap_sem);
return err;
}
@@ -1912,22 +1915,23 @@ EXPORT_SYMBOL(alloc_pages_current);
/* Slow path of a mempolicy duplicate */
struct mempolicy *__mpol_dup(struct mempolicy *old)
{
+ struct task_struct *tsk = current;
struct mempolicy *new = kmem_cache_alloc(policy_cache, GFP_KERNEL);
if (!new)
return ERR_PTR(-ENOMEM);
/* task's mempolicy is protected by alloc_lock */
- if (old == current->mempolicy) {
- task_lock(current);
+ if (old == tsk->mempolicy) {
+ task_lock(tsk);
*new = *old;
- task_unlock(current);
+ task_unlock(tsk);
} else
*new = *old;
rcu_read_lock();
if (current_cpuset_is_being_rebound()) {
- nodemask_t mems = cpuset_mems_allowed(current);
+ nodemask_t mems = cpuset_mems_allowed(tsk);
if (new->flags & MPOL_F_REBINDING)
mpol_rebind_policy(new, &mems, MPOL_REBIND_STEP2);
else
--
1.7.4
--
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