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mempolicy: mPOL_PREFERRED cleanups for "local allocation"

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Here are a couple of "cleanups" for MPOL_PREFERRED behavior when
v.preferred_node < 0 -- i.e., "local allocation":

1)  [do_]get_mempolicy() calls the now renamed get_policy_nodemask()
    to fetch the nodemask associated with a policy.  Currently,
    get_policy_nodemask() returns the set of nodes with memory, when
    the policy 'mode' is 'PREFERRED, and the preferred_node is < 0.
    Change to return an empty nodemask, as this is what was specified
    to achieve "local allocation".

2)  When a task is moved into a [new] cpuset, mpol_rebind_policy() is
    called to adjust any task and vma policy nodes to be valid in the
    new cpuset.  However, when the policy is MPOL_PREFERRED, and the
    preferred_node is <0, no rebind is necessary.  The "local allocation"
    indication is valid in any cpuset.  Existing code will "do the right
    thing" because node_remap() will just return the argument node when
    it is outside of the valid range of node ids.  However, I think it is
    clearer and cleaner to skip the remap explicitly in this case.

3)  mpol_to_str() produces a printable, "human readable" string from a
    struct mempolicy.  For MPOL_PREFERRED with preferred_node <0,  show
    "local", as this indicates local allocation, as the task migrates
    among nodes.  Note that this matches the usage of "local allocation"
    in libnuma() and numactl.  Without this change, I believe that node_set()
    [via set_bit()] will set bit 31, resulting in a misleading display.

Signed-off-by: Lee Schermerhorn <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Lee Schermerhorn 2008-04-28 02:13:20 -07:00 • committed by Linus Torvalds
commit 53f2556b67
1 changed files with 18 additions and 10 deletions
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28
mm/mempolicy.c
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@ -645,11 +645,9 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
*nodes = p->v.nodes;
break;
case MPOL_PREFERRED:
/* or use current node instead of memory_map? */
if (p->v.preferred_node < 0)
*nodes = node_states[N_HIGH_MEMORY];
else
if (p->v.preferred_node >= 0)
node_set(p->v.preferred_node, *nodes);
/* else return empty node mask for local allocation */
break;
default:
BUG();
@ -804,7 +802,7 @@ int do_migrate_pages(struct mm_struct *mm,
int err = 0;
nodemask_t tmp;
down_read(&mm->mmap_sem);
down_read(&mm->mmap_sem);
err = migrate_vmas(mm, from_nodes, to_nodes, flags);
if (err)
@ -1948,10 +1946,12 @@ void numa_default_policy(void)
}
/*
* Display pages allocated per node and memory policy via /proc.
* "local" is pseudo-policy: MPOL_PREFERRED with preferred_node == -1
* Used only for mpol_to_str()
*/
#define MPOL_LOCAL (MPOL_INTERLEAVE + 1)
static const char * const policy_types[] =
{ "default", "prefer", "bind", "interleave" };
{ "default", "prefer", "bind", "interleave", "local" };
/*
* Convert a mempolicy into a string.
@ -1962,6 +1962,7 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
{
char *p = buffer;
int l;
int nid;
nodemask_t nodes;
unsigned short mode;
unsigned short flags = pol ? pol->flags : 0;
@ -1978,7 +1979,11 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
case MPOL_PREFERRED:
nodes_clear(nodes);
node_set(pol->v.preferred_node, nodes);
nid = pol->v.preferred_node;
if (nid < 0)
mode = MPOL_LOCAL; /* pseudo-policy */
else
node_set(nid, nodes);
break;
case MPOL_BIND:
@ -1993,8 +1998,8 @@ static inline int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
}
l = strlen(policy_types[mode]);
if (buffer + maxlen < p + l + 1)
return -ENOSPC;
if (buffer + maxlen < p + l + 1)
return -ENOSPC;
strcpy(p, policy_types[mode]);
p += l;
@ -2093,6 +2098,9 @@ static inline void check_huge_range(struct vm_area_struct *vma,
}
#endif
/*
* Display pages allocated per node and memory policy via /proc.
*/
int show_numa_map(struct seq_file *m, void *v)
{
struct proc_maps_private *priv = m->private;