[PATCH 3/4] Embed zone_id information within the zonelist->zones pointer

Mel Gorman
2007-08-09T21:07:16Z

Using one zonelist per node requires very frequent use of zone_idx(). This
is costly as it involves a lookup of another structure and a substraction
operation. struct zone is aligned on a node-interleave boundary so the
pointer values of plenty of 0's at the least significant bits of the address.

This patch embeds the zone_id of a zone in the zonelist->zones pointers.
The real zone pointer is found using the zonelist_zone() helper function.
The ID of the zone is found using zonelist_zone_idx(). To avoid accidental
references, the zones field is renamed to _zones.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
---

include/linux/mmzone.h | 59 ++++++++++++++++++++++++++++++++++++++++----
mm/mempolicy.c | 22 ++++++++--------
mm/page_alloc.c | 36 +++++++++++++-------------
mm/vmstat.c | 4 +-
4 files changed, 85 insertions(+), 36 deletions(-)

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc1-mm2-010_use_zonelist/include/linux/mmzone.h linux-2.6.23-rc1-mm2-015_zoneid_zonelist/include/linux/mmzone.h
--- linux-2.6.23-rc1-mm2-010_use_zonelist/include/linux/mmzone.h 2007-08-09 15:08:15.000000000 +0100
+++ linux-2.6.23-rc1-mm2-015_zoneid_zonelist/include/linux/mmzone.h 2007-08-09 18:00:41.000000000 +0100
@@ -436,7 +436,9 @@ struct zonelist_cache;

struct zonelist {
struct zonelist_cache *zlcache_ptr; // NULL or &zlcache
- struct zone *zones[MAX_ZONES_PER_ZONELIST + 1]; // NULL delimited
+ struct zone *_zones[MAX_ZONES_PER_ZONELIST + 1]; // NULL delimited
+ // Access with
+ // zonelist_zone()
#ifdef CONFIG_NUMA
struct zonelist_cache zlcache; // optional ...
#endif
@@ -676,12 +678,57 @@ static inline struct zonelist *node_zone
return &NODE_DATA(nid)->node_zonelist;
}

+#if defined(CONFIG_SMP) && INTERNODE_CACHE_SHIFT > ZONES_SHIFT
+
+/* Similar to ZONES_MASK but is not available in this context */
+#define ZONELIST_ZONEIDX_MASK ((1UL << ZONES_SHIFT) - 1)
+
+/* zone_id is small enough to fit at bottom of zone pointer in zonelist */
+static inline struct zone *zonelist_zone(struct zone *zone)
+{
+ return (struct zone *)((unsigned long)zone & ~ZONELIST_ZONEIDX_MASK);
+}
+
+
+static inline int zonelist_zone_idx(struct zone *zone)
+{
+ /* ZONES_MASK not available in this context */
+ return (unsigned long)zone & ZONELIST_ZONEIDX_MASK;
+}
+
+static inline struct zone *encode_zone_idx(struct zone *zone)
+{
+ struct zone *encoded;
+
+ encoded = (struct zone *)((unsigned long)zone | zone_idx(zone));
+ BUG_ON(zonelist_zone(encoded) != zone);
+ return encoded;
+}
+#else
+static inline struct zone *zonelist_zone(struct zone *zone)
+{
+ return zone;
+}
+
+static inline int zonelist_zone_idx(struct zone *zone)
+{
+ return zone_idx(zone);
+}
+
+static inline struct zone *encode_zone_idx(struct zone *zone)
+{
+ return zone;
+}
+#endif
+
/* Returns the first zone at or below highest_zoneidx in a zonelist */
static inline struct zone **first_zones_zonelist(struct zonelist *zonelist,
enum zone_type highest_zoneidx)
{
struct zone **z;
- for (z = zonelist->zones; *z && zone_idx(*z) > highest_zoneidx; z++);
+ for (z = zonelist->_zones;
+ *z && zonelist_zone_idx(*z) > highest_zoneidx;
+ z++);
return z;
}

@@ -689,7 +736,9 @@ static inline struct zone **first_zones_
static inline struct zone **next_zones_zonelist(struct zone **z,
enum zone_type highest_zoneidx)
{
- for (++z; *z && zone_idx(*z) > highest_zoneidx; z++);
+ for (++z;
+ *z && zonelist_zone_idx(*z) > highest_zoneidx;
+ z++);
return z;
}

@@ -703,9 +752,9 @@ static inline struct zone **next_zones_z
* This iterator iterates though all zones at or below a given zone index.
*/
#define for_each_zone_zonelist(zone, z, zlist, highidx) \
- for (z = first_zones_zonelist(zlist, highidx), zone = *z; \
+ for (z = first_zones_zonelist(zlist, highidx), zone = zonelist_zone(*z); \
zone; \
- z = next_zones_zonelist(z, highidx), zone = *z)
+ z = next_zones_zonelist(z, highidx), zone = zonelist_zone(*z))

#ifdef CONFIG_SPARSEMEM
#include <asm/sparsemem.h>
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc1-mm2-010_use_zonelist/mm/mempolicy.c linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/mempolicy.c
--- linux-2.6.23-rc1-mm2-010_use_zonelist/mm/mempolicy.c 2007-08-09 18:34:00.000000000 +0100
+++ linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/mempolicy.c 2007-08-09 18:33:51.000000000 +0100
@@ -156,7 +156,7 @@ static struct zonelist *bind_zonelist(no
for_each_node_mask(nd, *nodes) {
struct zone *z = &NODE_DATA(nd)->node_zones[k];
if (z->present_pages > 0)
- zl->zones[num++] = z;
+ zl->_zones[num++] = encode_zone_idx(z);
}
if (k == 0)
break;
@@ -166,7 +166,7 @@ static struct zonelist *bind_zonelist(no
kfree(zl);
return ERR_PTR(-EINVAL);
}
- zl->zones[num] = NULL;
+ zl->_zones[num] = NULL;
return zl;
}

@@ -486,8 +486,8 @@ static void get_zonemask(struct mempolic
nodes_clear(*nodes);
switch (p->policy) {
case MPOL_BIND:
- for (i = 0; p->v.zonelist->zones[i]; i++)
- node_set(zone_to_nid(p->v.zonelist->zones[i]),
+ for (i = 0; p->v.zonelist->_zones[i]; i++)
+ node_set(zone_to_nid(zonelist_zone(p->v.zonelist->_zones[i])),
*nodes);
break;
case MPOL_DEFAULT:
@@ -1154,7 +1154,7 @@ unsigned slab_node(struct mempolicy *pol
* Follow bind policy behavior and start allocation at the
* first node.
*/
- return zone_to_nid(policy->v.zonelist->zones[0]);
+ return zone_to_nid(zonelist_zone(policy->v.zonelist->_zones[0]));

case MPOL_PREFERRED:
if (policy->v.preferred_node >= 0)
@@ -1232,7 +1232,7 @@ static struct page *alloc_page_interleav

zl = node_zonelist(nid);
page = __alloc_pages(gfp, order, zl);
- if (page && page_zone(page) == zl->zones[0])
+ if (page && page_zone(page) == zonelist_zone(zl->_zones[0]))
inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
return page;
}
@@ -1356,10 +1356,10 @@ int __mpol_equal(struct mempolicy *a, st
return a->v.preferred_node == b->v.preferred_node;
case MPOL_BIND: {
int i;
- for (i = 0; a->v.zonelist->zones[i]; i++)
- if (a->v.zonelist->zones[i] != b->v.zonelist->zones[i])
+ for (i = 0; a->v.zonelist->_zones[i]; i++)
+ if (zonelist_zone(a->v.zonelist->_zones[i]) != zonelist_zone(b->v.zonelist->_zones[i]))
return 0;
- return b->v.zonelist->zones[i] == NULL;
+ return b->v.zonelist->_zones[i] == NULL;
}
default:
BUG();
@@ -1682,8 +1682,8 @@ static void mpol_rebind_policy(struct me
struct zonelist *zonelist;

nodes_clear(nodes);
- for (z = pol->v.zonelist->zones; *z; z++)
- node_set(zone_to_nid(*z), nodes);
+ for (z = pol->v.zonelist->_zones; *z; z++)
+ node_set(zone_to_nid(zonelist_zone(*z)), nodes);
nodes_remap(tmp, nodes, *mpolmask, *newmask);
nodes = tmp;

diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc1-mm2-010_use_zonelist/mm/page_alloc.c linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/page_alloc.c
--- linux-2.6.23-rc1-mm2-010_use_zonelist/mm/page_alloc.c 2007-08-09 15:04:19.000000000 +0100
+++ linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/page_alloc.c 2007-08-09 15:52:12.000000000 +0100
@@ -1360,7 +1360,7 @@ static int zlc_zone_worth_trying(struct
if (!zlc)
return 1;

- i = z - zonelist->zones;
+ i = z - zonelist->_zones;
n = zlc->z_to_n[i];

/* This zone is worth trying if it is allowed but not full */
@@ -1381,7 +1381,7 @@ static void zlc_mark_zone_full(struct zo
if (!zlc)
return;

- i = z - zonelist->zones;
+ i = z - zonelist->_zones;

set_bit(i, zlc->fullzones);
}
@@ -1414,7 +1414,7 @@ get_page_from_freelist(gfp_t gfp_mask, u
{
struct zone **z;
struct page *page = NULL;
- int classzone_idx = zone_idx(zonelist->zones[0]);
+ int classzone_idx = zonelist_zone_idx(zonelist->_zones[0]);
struct zone *zone;
enum zone_type high_zoneidx = gfp_zone(gfp_mask);
nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
@@ -1431,7 +1431,7 @@ zonelist_scan:
!zlc_zone_worth_trying(zonelist, z, allowednodes))
continue;
if (unlikely(NUMA_BUILD && (gfp_mask & __GFP_THISNODE) &&
- zone->zone_pgdat != zonelist->zones[0]->zone_pgdat))
+ zone->zone_pgdat != zonelist_zone(zonelist->_zones[0])->zone_pgdat))
break;
if ((alloc_flags & ALLOC_CPUSET) &&
!cpuset_zone_allowed_softwall(zone, gfp_mask))
@@ -1554,9 +1554,9 @@ __alloc_pages(gfp_t gfp_mask, unsigned i
return NULL;

restart:
- z = zonelist->zones; /* the list of zones suitable for gfp_mask */
+ z = zonelist->_zones; /* the list of zones suitable for gfp_mask */

- if (unlikely(*z == NULL)) {
+ if (unlikely(zonelist_zone(*z) == NULL)) {
/* Should this ever happen?? */
return NULL;
}
@@ -1577,8 +1577,8 @@ restart:
if (NUMA_BUILD && (gfp_mask & GFP_THISNODE) == GFP_THISNODE)
goto nopage;

- for (z = zonelist->zones; *z; z++)
- wakeup_kswapd(*z, order);
+ for (z = zonelist->_zones; *z; z++)
+ wakeup_kswapd(zonelist_zone(*z), order);

/*
* OK, we're below the kswapd watermark and have kicked background
@@ -1974,7 +1974,7 @@ static int build_zonelists_node(pg_data_
zone_type--;
zone = pgdat->node_zones + zone_type;
if (populated_zone(zone)) {
- zonelist->zones[nr_zones++] = zone;
+ zonelist->_zones[nr_zones++] = encode_zone_idx(zone);
check_highest_zone(zone_type);
}

@@ -2150,10 +2150,10 @@ static void build_zonelists_in_node_orde
struct zonelist *zonelist;

zonelist = &pgdat->node_zonelist;
- for (j = 0; zonelist->zones[j] != NULL; j++)
+ for (j = 0; zonelist->_zones[j] != NULL; j++)
;
j = build_zonelists_node(NODE_DATA(node), zonelist, j, MAX_NR_ZONES-1);
- zonelist->zones[j] = NULL;
+ zonelist->_zones[j] = NULL;
}

/*
@@ -2178,12 +2178,12 @@ static void build_zonelists_in_zone_orde
node = node_order[j];
z = &NODE_DATA(node)->node_zones[zone_type];
if (populated_zone(z)) {
- zonelist->zones[pos++] = z;
+ zonelist->_zones[pos++] = encode_zone_idx(z);
check_highest_zone(zone_type);
}
}
}
- zonelist->zones[pos] = NULL;
+ zonelist->_zones[pos] = NULL;
}

static int default_zonelist_order(void)
@@ -2257,7 +2257,7 @@ static void build_zonelists(pg_data_t *p

/* initialize zonelist */
zonelist = &pgdat->node_zonelist;
- zonelist->zones[0] = NULL;
+ zonelist->_zones[0] = NULL;

/* NUMA-aware ordering of nodes */
local_node = pgdat->node_id;
@@ -2304,7 +2304,6 @@ static void build_zonelists(pg_data_t *p
/* Construct the zonelist performance cache - see further mmzone.h */
static void build_zonelist_cache(pg_data_t *pgdat)
{
- int i;
struct zonelist *zonelist;
struct zonelist_cache *zlc;
struct zone **z;
@@ -2312,8 +2311,9 @@ static void build_zonelist_cache(pg_data
zonelist = &pgdat->node_zonelist;
zonelist->zlcache_ptr = zlc = &zonelist->zlcache;
bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
- for (z = zonelist->zones; *z; z++)
- zlc->z_to_n[z - zonelist->zones] = zone_to_nid(*z);
+ for (z = zonelist->_zones; *z; z++)
+ zlc->z_to_n[z - zonelist->_zones] =
+ zone_to_nid(zonelist_zone(*z));
}

@@ -2356,7 +2356,7 @@ static void build_zonelists(pg_data_t *p
MAX_NR_ZONES-1);
}

- zonelist->zones[j] = NULL;
+ zonelist->_zones[j] = NULL;
}

/* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc1-mm2-010_use_zonelist/mm/vmstat.c linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/vmstat.c
--- linux-2.6.23-rc1-mm2-010_use_zonelist/mm/vmstat.c 2007-08-07 14:45:11.000000000 +0100
+++ linux-2.6.23-rc1-mm2-015_zoneid_zonelist/mm/vmstat.c 2007-08-09 15:52:12.000000000 +0100
@@ -365,11 +365,11 @@ void refresh_cpu_vm_stats(int cpu)
*/
void zone_statistics(struct zonelist *zonelist, struct zone *z)
{
- if (z->zone_pgdat == zonelist->zones[0]->zone_pgdat) {
+ if (z->zone_pgdat == zonelist_zone(zonelist->_zones[0])->zone_pgdat) {
__inc_zone_state(z, NUMA_HIT);
} else {
__inc_zone_state(z, NUMA_MISS);
- __inc_zone_state(zonelist->zones[0], NUMA_FOREIGN);
+ __inc_zone_state(zonelist_zone(zonelist->_zones[0]), NUMA_FOREIGN);
}
if (z->node == numa_node_id())
__inc_zone_state(z, NUMA_LOCAL);