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mempolicy: add MPOL_F_RELATIVE_NODES flag

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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: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
David Rientjes 2008-04-28 02:12:30 -07:00 committed by Linus Torvalds
parent 7ea931c9fc
commit 4c50bc0116
3 changed files with 39 additions and 3 deletions
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3
include/linux/mempolicy.h
View File

@ -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 */

33
mm/mempolicy.c
View File

@ -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)) {

6
mm/shmem.c
View File

@ -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 */