Commit 4c50bc01 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mempolicy: add MPOL_F_RELATIVE_NODES flag 



Adds another optional mode flag, MPOL_F_RELATIVE_NODES, that specifies
nodemasks passed via set_mempolicy() or mbind() should be considered relative
to the current task's mems_allowed.

When the mempolicy is created, the passed nodemask is folded and mapped onto
the current task's mems_allowed.  For example, consider a task using
set_mempolicy() to pass MPOL_INTERLEAVE | MPOL_F_RELATIVE_NODES with a
nodemask of 1-3.  If current's mems_allowed is 4-7, the effected nodemask is
5-7 (the second, third, and fourth node of mems_allowed).

If the same task is attached to a cpuset, the mempolicy nodemask is rebound
each time the mems are changed.  Some possible rebinds and results are:

	mems			result
	1-3			1-3
	1-7			2-4
	1,5-6			1,5-6
	1,5-7			5-7

Likewise, the zonelist built for MPOL_BIND acts on the set of zones assigned
to the resultant nodemask from the relative remap.

In the MPOL_PREFERRED case, the preferred node is remapped from the currently
effected nodemask to the relative nodemask.

This mempolicy mode flag was conceived of by Paul Jackson <pj@sgi.com>.

Cc: Paul Jackson <pj@sgi.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 7ea931c9

include/linux/mempolicy.h

+2 −1
Original line number Diff line number Diff line
@@ -25,12 +25,13 @@ enum { 


/* Flags for set_mempolicy */

#define MPOL_F_STATIC_NODES	(1 << 15)

#define MPOL_F_RELATIVE_NODES	(1 << 14)



/*

 * MPOL_MODE_FLAGS is the union of all possible optional mode flags passed to

 * either set_mempolicy() or mbind().

 */

#define MPOL_MODE_FLAGS	(MPOL_F_STATIC_NODES)

#define MPOL_MODE_FLAGS	(MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES)



/* Flags for get_mempolicy */

#define MPOL_F_NODE	(1<<0)	/* return next IL mode instead of node mask */

mm/mempolicy.c

+31 −2
Original line number Diff line number Diff line
@@ -136,7 +136,15 @@ static int is_valid_nodemask(nodemask_t *nodemask) 


static inline int mpol_store_user_nodemask(const struct mempolicy *pol)

{

	return pol->flags & MPOL_F_STATIC_NODES;

	return pol->flags & (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES);

}



static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,

				   const nodemask_t *rel)

{

	nodemask_t tmp;

	nodes_fold(tmp, *orig, nodes_weight(*rel));

	nodes_onto(*ret, tmp, *rel);

}



/* Create a new policy */
@@ -157,7 +165,12 @@ static struct mempolicy *mpol_new(unsigned short mode, unsigned short flags, 
		return ERR_PTR(-ENOMEM);

	atomic_set(&policy->refcnt, 1);

	cpuset_update_task_memory_state();

	nodes_and(cpuset_context_nmask, *nodes, cpuset_current_mems_allowed);

	if (flags & MPOL_F_RELATIVE_NODES)

		mpol_relative_nodemask(&cpuset_context_nmask, nodes,

				       &cpuset_current_mems_allowed);

	else

		nodes_and(cpuset_context_nmask, *nodes,

			  cpuset_current_mems_allowed);

	switch (mode) {

	case MPOL_INTERLEAVE:

		if (nodes_empty(*nodes) || nodes_empty(cpuset_context_nmask))
@@ -873,6 +886,9 @@ asmlinkage long sys_mbind(unsigned long start, unsigned long len, 
	mode &= ~MPOL_MODE_FLAGS;

	if (mode >= MPOL_MAX)

		return -EINVAL;

	if ((mode_flags & MPOL_F_STATIC_NODES) &&

	    (mode_flags & MPOL_F_RELATIVE_NODES))

		return -EINVAL;

	err = get_nodes(&nodes, nmask, maxnode);

	if (err)

		return err;
@@ -891,6 +907,8 @@ asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask, 
	mode &= ~MPOL_MODE_FLAGS;

	if ((unsigned int)mode >= MPOL_MAX)

		return -EINVAL;

	if ((flags & MPOL_F_STATIC_NODES) && (flags & MPOL_F_RELATIVE_NODES))

		return -EINVAL;

	err = get_nodes(&nodes, nmask, maxnode);

	if (err)

		return err;
@@ -1745,10 +1763,12 @@ static void mpol_rebind_policy(struct mempolicy *pol, 
{

	nodemask_t tmp;

	int static_nodes;

	int relative_nodes;



	if (!pol)

		return;

	static_nodes = pol->flags & MPOL_F_STATIC_NODES;

	relative_nodes = pol->flags & MPOL_F_RELATIVE_NODES;

	if (!mpol_store_user_nodemask(pol) &&

	    nodes_equal(pol->w.cpuset_mems_allowed, *newmask))

		return;
@@ -1761,6 +1781,9 @@ static void mpol_rebind_policy(struct mempolicy *pol, 
	case MPOL_INTERLEAVE:

		if (static_nodes)

			nodes_and(tmp, pol->w.user_nodemask, *newmask);

		else if (relative_nodes)

			mpol_relative_nodemask(&tmp, &pol->w.user_nodemask,

					       newmask);

		else {

			nodes_remap(tmp, pol->v.nodes,

				    pol->w.cpuset_mems_allowed, *newmask);
@@ -1783,6 +1806,10 @@ static void mpol_rebind_policy(struct mempolicy *pol, 
				pol->v.preferred_node = node;

			else

				pol->v.preferred_node = -1;

		} else if (relative_nodes) {

			mpol_relative_nodemask(&tmp, &pol->w.user_nodemask,

					       newmask);

			pol->v.preferred_node = first_node(tmp);

		} else {

			pol->v.preferred_node = node_remap(pol->v.preferred_node,

					pol->w.cpuset_mems_allowed, *newmask);
@@ -1878,6 +1905,8 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol) 


		if (flags & MPOL_F_STATIC_NODES)

			p += sprintf(p, "%sstatic", need_bar++ ? "|" : "");

		if (flags & MPOL_F_RELATIVE_NODES)

			p += sprintf(p, "%srelative", need_bar++ ? "|" : "");

	}



	if (!nodes_empty(nodes)) {

mm/shmem.c

+6 −0
Original line number Diff line number Diff line
@@ -1128,6 +1128,12 @@ static int shmem_parse_mpol(char *value, unsigned short *policy, 
	if (flags) {

		if (!strcmp(flags, "static"))

			*mode_flags |= MPOL_F_STATIC_NODES;

		if (!strcmp(flags, "relative"))

			*mode_flags |= MPOL_F_RELATIVE_NODES;



		if ((*mode_flags & MPOL_F_STATIC_NODES) &&

		    (*mode_flags & MPOL_F_RELATIVE_NODES))

			err = 1;

	}

out:

	/* Restore string for error message */

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