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Commit cf2a473c authored by Paul Jackson's avatar Paul Jackson Committed by Linus Torvalds
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[PATCH] cpuset: combine refresh_mems and update_mems 



The important code paths through alloc_pages_current() and alloc_page_vma(),
by which most kernel page allocations go, both called
cpuset_update_current_mems_allowed(), which in turn called refresh_mems().
-Both- of these latter two routines did a tasklock, got the tasks cpuset
pointer, and checked for out of date cpuset->mems_generation.

That was a silly duplication of code and waste of CPU cycles on an important
code path.

Consolidated those two routines into a single routine, called
cpuset_update_task_memory_state(), since it updates more than just
mems_allowed.

Changed all callers of either routine to call the new consolidated routine.

Signed-off-by: default avatarPaul Jackson <pj@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent b4b26418

include/linux/cpuset.h

+2 −2
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ extern void cpuset_fork(struct task_struct *p); 
extern void cpuset_exit(struct task_struct *p);

extern cpumask_t cpuset_cpus_allowed(const struct task_struct *p);

void cpuset_init_current_mems_allowed(void);

void cpuset_update_current_mems_allowed(void);

void cpuset_update_task_memory_state(void);

#define cpuset_nodes_subset_current_mems_allowed(nodes) \

		nodes_subset((nodes), current->mems_allowed)

int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl);
@@ -51,7 +51,7 @@ static inline cpumask_t cpuset_cpus_allowed(struct task_struct *p) 
}



static inline void cpuset_init_current_mems_allowed(void) {}

static inline void cpuset_update_current_mems_allowed(void) {}

static inline void cpuset_update_task_memory_state(void) {}

#define cpuset_nodes_subset_current_mems_allowed(nodes) (1)



static inline int cpuset_zonelist_valid_mems_allowed(struct zonelist *zl)

kernel/cpuset.c

+41 −54
Original line number Diff line number Diff line
@@ -584,13 +584,26 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) 
	BUG_ON(!nodes_intersects(*pmask, node_online_map));

}



/*

 * Refresh current tasks mems_allowed and mems_generation from current

 * tasks cpuset.

/**

 * cpuset_update_task_memory_state - update task memory placement

 *

 * If the current tasks cpusets mems_allowed changed behind our

 * backs, update current->mems_allowed, mems_generation and task NUMA

 * mempolicy to the new value.

 *

 * Task mempolicy is updated by rebinding it relative to the

 * current->cpuset if a task has its memory placement changed.

 * Do not call this routine if in_interrupt().

 *

 * Call without callback_sem or task_lock() held.  May be called with

 * or without manage_sem held.  Will acquire task_lock() and might

 * acquire callback_sem during call.

 * Call without callback_sem or task_lock() held.  May be called

 * with or without manage_sem held.  Except in early boot or

 * an exiting task, when tsk->cpuset is NULL, this routine will

 * acquire task_lock().  We don't need to use task_lock to guard

 * against another task changing a non-NULL cpuset pointer to NULL,

 * as that is only done by a task on itself, and if the current task

 * is here, it is not simultaneously in the exit code NULL'ing its

 * cpuset pointer.  This routine also might acquire callback_sem and

 * current->mm->mmap_sem during call.

 *

 * The task_lock() is required to dereference current->cpuset safely.

 * Without it, we could pick up the pointer value of current->cpuset
@@ -605,32 +618,36 @@ static void guarantee_online_mems(const struct cpuset *cs, nodemask_t *pmask) 
 * task has been modifying its cpuset.

 */



static void refresh_mems(void)

void cpuset_update_task_memory_state()

{

	int my_cpusets_mem_gen;

	struct task_struct *tsk = current;

	struct cpuset *cs = tsk->cpuset;



	task_lock(current);

	my_cpusets_mem_gen = current->cpuset->mems_generation;

	task_unlock(current);

	if (unlikely(!cs))

		return;



	if (current->cpuset_mems_generation != my_cpusets_mem_gen) {

		struct cpuset *cs;

		nodemask_t oldmem = current->mems_allowed;

	task_lock(tsk);

	my_cpusets_mem_gen = cs->mems_generation;

	task_unlock(tsk);



	if (my_cpusets_mem_gen != tsk->cpuset_mems_generation) {

		nodemask_t oldmem = tsk->mems_allowed;

		int migrate;



		down(&callback_sem);

		task_lock(current);

		cs = current->cpuset;

		task_lock(tsk);

		cs = tsk->cpuset;	/* Maybe changed when task not locked */

		migrate = is_memory_migrate(cs);

		guarantee_online_mems(cs, &current->mems_allowed);

		current->cpuset_mems_generation = cs->mems_generation;

		task_unlock(current);

		guarantee_online_mems(cs, &tsk->mems_allowed);

		tsk->cpuset_mems_generation = cs->mems_generation;

		task_unlock(tsk);

		up(&callback_sem);

		if (!nodes_equal(oldmem, current->mems_allowed)) {

			numa_policy_rebind(&oldmem, &current->mems_allowed);

		numa_policy_rebind(&oldmem, &tsk->mems_allowed);

		if (!nodes_equal(oldmem, tsk->mems_allowed)) {

			if (migrate) {

				do_migrate_pages(current->mm, &oldmem,

					&current->mems_allowed,

				do_migrate_pages(tsk->mm, &oldmem,

					&tsk->mems_allowed,

					MPOL_MF_MOVE_ALL);

			}

		}
@@ -1630,7 +1647,7 @@ static long cpuset_create(struct cpuset *parent, const char *name, int mode) 
		return -ENOMEM;



	down(&manage_sem);

	refresh_mems();

	cpuset_update_task_memory_state();

	cs->flags = 0;

	if (notify_on_release(parent))

		set_bit(CS_NOTIFY_ON_RELEASE, &cs->flags);
@@ -1688,7 +1705,7 @@ static int cpuset_rmdir(struct inode *unused_dir, struct dentry *dentry) 
	/* the vfs holds both inode->i_sem already */



	down(&manage_sem);

	refresh_mems();

	cpuset_update_task_memory_state();

	if (atomic_read(&cs->count) > 0) {

		up(&manage_sem);

		return -EBUSY;
@@ -1872,36 +1889,6 @@ void cpuset_init_current_mems_allowed(void) 
	current->mems_allowed = NODE_MASK_ALL;

}



/**

 * cpuset_update_current_mems_allowed - update mems parameters to new values

 *

 * If the current tasks cpusets mems_allowed changed behind our backs,

 * update current->mems_allowed and mems_generation to the new value.

 * Do not call this routine if in_interrupt().

 *

 * Call without callback_sem or task_lock() held.  May be called

 * with or without manage_sem held.  Unless exiting, it will acquire

 * task_lock().  Also might acquire callback_sem during call to

 * refresh_mems().

 */



void cpuset_update_current_mems_allowed(void)

{

	struct cpuset *cs;

	int need_to_refresh = 0;



	task_lock(current);

	cs = current->cpuset;

	if (!cs)

		goto done;

	if (current->cpuset_mems_generation != cs->mems_generation)

		need_to_refresh = 1;

done:

	task_unlock(current);

	if (need_to_refresh)

		refresh_mems();

}



/**

 * cpuset_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed

 * @zl: the zonelist to be checked

mm/mempolicy.c

+5 −5
Original line number Diff line number Diff line
@@ -387,7 +387,7 @@ static int contextualize_policy(int mode, nodemask_t *nodes) 
	if (!nodes)

		return 0;



	cpuset_update_current_mems_allowed();

	cpuset_update_task_memory_state();

	if (!cpuset_nodes_subset_current_mems_allowed(*nodes))

		return -EINVAL;

	return mpol_check_policy(mode, nodes);
@@ -461,7 +461,7 @@ long do_get_mempolicy(int *policy, nodemask_t *nmask, 
	struct vm_area_struct *vma = NULL;

	struct mempolicy *pol = current->mempolicy;



	cpuset_update_current_mems_allowed();

	cpuset_update_task_memory_state();

	if (flags & ~(unsigned long)(MPOL_F_NODE|MPOL_F_ADDR))

		return -EINVAL;

	if (flags & MPOL_F_ADDR) {
@@ -1089,7 +1089,7 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr) 
{

	struct mempolicy *pol = get_vma_policy(current, vma, addr);



	cpuset_update_current_mems_allowed();

	cpuset_update_task_memory_state();



	if (unlikely(pol->policy == MPOL_INTERLEAVE)) {

		unsigned nid;
@@ -1115,7 +1115,7 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr) 
 *	interrupt context and apply the current process NUMA policy.

 *	Returns NULL when no page can be allocated.

 *

 *	Don't call cpuset_update_current_mems_allowed() unless

 *	Don't call cpuset_update_task_memory_state() unless

 *	1) it's ok to take cpuset_sem (can WAIT), and

 *	2) allocating for current task (not interrupt).

 */
@@ -1124,7 +1124,7 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order) 
	struct mempolicy *pol = current->mempolicy;



	if ((gfp & __GFP_WAIT) && !in_interrupt())

		cpuset_update_current_mems_allowed();

		cpuset_update_task_memory_state();

	if (!pol || in_interrupt())

		pol = &default_policy;

	if (pol->policy == MPOL_INTERLEAVE)