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-rw-r--r--mm/page_alloc.c188
1 files changed, 181 insertions, 7 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 23bc5bcbdcf..230771d3c6b 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -918,6 +918,126 @@ int zone_watermark_ok(struct zone *z, int order, unsigned long mark,
return 1;
}
+#ifdef CONFIG_NUMA
+/*
+ * zlc_setup - Setup for "zonelist cache". Uses cached zone data to
+ * skip over zones that are not allowed by the cpuset, or that have
+ * been recently (in last second) found to be nearly full. See further
+ * comments in mmzone.h. Reduces cache footprint of zonelist scans
+ * that have to skip over alot of full or unallowed zones.
+ *
+ * If the zonelist cache is present in the passed in zonelist, then
+ * returns a pointer to the allowed node mask (either the current
+ * tasks mems_allowed, or node_online_map.)
+ *
+ * If the zonelist cache is not available for this zonelist, does
+ * nothing and returns NULL.
+ *
+ * If the fullzones BITMAP in the zonelist cache is stale (more than
+ * a second since last zap'd) then we zap it out (clear its bits.)
+ *
+ * We hold off even calling zlc_setup, until after we've checked the
+ * first zone in the zonelist, on the theory that most allocations will
+ * be satisfied from that first zone, so best to examine that zone as
+ * quickly as we can.
+ */
+static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
+{
+ struct zonelist_cache *zlc; /* cached zonelist speedup info */
+ nodemask_t *allowednodes; /* zonelist_cache approximation */
+
+ zlc = zonelist->zlcache_ptr;
+ if (!zlc)
+ return NULL;
+
+ if (jiffies - zlc->last_full_zap > 1 * HZ) {
+ bitmap_zero(zlc->fullzones, MAX_ZONES_PER_ZONELIST);
+ zlc->last_full_zap = jiffies;
+ }
+
+ allowednodes = !in_interrupt() && (alloc_flags & ALLOC_CPUSET) ?
+ &cpuset_current_mems_allowed :
+ &node_online_map;
+ return allowednodes;
+}
+
+/*
+ * Given 'z' scanning a zonelist, run a couple of quick checks to see
+ * if it is worth looking at further for free memory:
+ * 1) Check that the zone isn't thought to be full (doesn't have its
+ * bit set in the zonelist_cache fullzones BITMAP).
+ * 2) Check that the zones node (obtained from the zonelist_cache
+ * z_to_n[] mapping) is allowed in the passed in allowednodes mask.
+ * Return true (non-zero) if zone is worth looking at further, or
+ * else return false (zero) if it is not.
+ *
+ * This check -ignores- the distinction between various watermarks,
+ * such as GFP_HIGH, GFP_ATOMIC, PF_MEMALLOC, ... If a zone is
+ * found to be full for any variation of these watermarks, it will
+ * be considered full for up to one second by all requests, unless
+ * we are so low on memory on all allowed nodes that we are forced
+ * into the second scan of the zonelist.
+ *
+ * In the second scan we ignore this zonelist cache and exactly
+ * apply the watermarks to all zones, even it is slower to do so.
+ * We are low on memory in the second scan, and should leave no stone
+ * unturned looking for a free page.
+ */
+static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
+ nodemask_t *allowednodes)
+{
+ struct zonelist_cache *zlc; /* cached zonelist speedup info */
+ int i; /* index of *z in zonelist zones */
+ int n; /* node that zone *z is on */
+
+ zlc = zonelist->zlcache_ptr;
+ if (!zlc)
+ return 1;
+
+ i = z - zonelist->zones;
+ n = zlc->z_to_n[i];
+
+ /* This zone is worth trying if it is allowed but not full */
+ return node_isset(n, *allowednodes) && !test_bit(i, zlc->fullzones);
+}
+
+/*
+ * Given 'z' scanning a zonelist, set the corresponding bit in
+ * zlc->fullzones, so that subsequent attempts to allocate a page
+ * from that zone don't waste time re-examining it.
+ */
+static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
+{
+ struct zonelist_cache *zlc; /* cached zonelist speedup info */
+ int i; /* index of *z in zonelist zones */
+
+ zlc = zonelist->zlcache_ptr;
+ if (!zlc)
+ return;
+
+ i = z - zonelist->zones;
+
+ set_bit(i, zlc->fullzones);
+}
+
+#else /* CONFIG_NUMA */
+
+static nodemask_t *zlc_setup(struct zonelist *zonelist, int alloc_flags)
+{
+ return NULL;
+}
+
+static int zlc_zone_worth_trying(struct zonelist *zonelist, struct zone **z,
+ nodemask_t *allowednodes)
+{
+ return 1;
+}
+
+static void zlc_mark_zone_full(struct zonelist *zonelist, struct zone **z)
+{
+}
+#endif /* CONFIG_NUMA */
+
/*
* get_page_from_freelist goes through the zonelist trying to allocate
* a page.
@@ -926,23 +1046,32 @@ static struct page *
get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
struct zonelist *zonelist, int alloc_flags)
{
- struct zone **z = zonelist->zones;
+ struct zone **z;
struct page *page = NULL;
- int classzone_idx = zone_idx(*z);
+ int classzone_idx = zone_idx(zonelist->zones[0]);
struct zone *zone;
+ nodemask_t *allowednodes = NULL;/* zonelist_cache approximation */
+ int zlc_active = 0; /* set if using zonelist_cache */
+ int did_zlc_setup = 0; /* just call zlc_setup() one time */
+zonelist_scan:
/*
- * Go through the zonelist once, looking for a zone with enough free.
+ * Scan zonelist, looking for a zone with enough free.
* See also cpuset_zone_allowed() comment in kernel/cpuset.c.
*/
+ z = zonelist->zones;
+
do {
+ if (NUMA_BUILD && zlc_active &&
+ !zlc_zone_worth_trying(zonelist, z, allowednodes))
+ continue;
zone = *z;
if (unlikely(NUMA_BUILD && (gfp_mask & __GFP_THISNODE) &&
zone->zone_pgdat != zonelist->zones[0]->zone_pgdat))
break;
if ((alloc_flags & ALLOC_CPUSET) &&
!cpuset_zone_allowed(zone, gfp_mask))
- continue;
+ goto try_next_zone;
if (!(alloc_flags & ALLOC_NO_WATERMARKS)) {
unsigned long mark;
@@ -956,15 +1085,30 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order,
classzone_idx, alloc_flags)) {
if (!zone_reclaim_mode ||
!zone_reclaim(zone, gfp_mask, order))
- continue;
+ goto this_zone_full;
}
}
page = buffered_rmqueue(zonelist, zone, order, gfp_mask);
if (page)
break;
-
+this_zone_full:
+ if (NUMA_BUILD)
+ zlc_mark_zone_full(zonelist, z);
+try_next_zone:
+ if (NUMA_BUILD && !did_zlc_setup) {
+ /* we do zlc_setup after the first zone is tried */
+ allowednodes = zlc_setup(zonelist, alloc_flags);
+ zlc_active = 1;
+ did_zlc_setup = 1;
+ }
} while (*(++z) != NULL);
+
+ if (unlikely(NUMA_BUILD && page == NULL && zlc_active)) {
+ /* Disable zlc cache for second zonelist scan */
+ zlc_active = 0;
+ goto zonelist_scan;
+ }
return page;
}
@@ -1535,6 +1679,24 @@ static void __meminit build_zonelists(pg_data_t *pgdat)
}
}
+/* Construct the zonelist performance cache - see further mmzone.h */
+static void __meminit build_zonelist_cache(pg_data_t *pgdat)
+{
+ int i;
+
+ for (i = 0; i < MAX_NR_ZONES; i++) {
+ struct zonelist *zonelist;
+ struct zonelist_cache *zlc;
+ struct zone **z;
+
+ zonelist = pgdat->node_zonelists + i;
+ 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);
+ }
+}
+
#else /* CONFIG_NUMA */
static void __meminit build_zonelists(pg_data_t *pgdat)
@@ -1572,14 +1734,26 @@ static void __meminit build_zonelists(pg_data_t *pgdat)
}
}
+/* non-NUMA variant of zonelist performance cache - just NULL zlcache_ptr */
+static void __meminit build_zonelist_cache(pg_data_t *pgdat)
+{
+ int i;
+
+ for (i = 0; i < MAX_NR_ZONES; i++)
+ pgdat->node_zonelists[i].zlcache_ptr = NULL;
+}
+
#endif /* CONFIG_NUMA */
/* return values int ....just for stop_machine_run() */
static int __meminit __build_all_zonelists(void *dummy)
{
int nid;
- for_each_online_node(nid)
+
+ for_each_online_node(nid) {
build_zonelists(NODE_DATA(nid));
+ build_zonelist_cache(NODE_DATA(nid));
+ }
return 0;
}