[PATCH] Reduce size of huge boot per_cpu_pageset

Reduce size of the huge per_cpu_pageset structure in __initdata introduced
into mm1 with the pageset localization patchset.  Use one specially
configured pageset per cpu for all zones and nodes during bootup.

- Avoid duplication of pageset initialization code.
- do the adding to the pageset list before potential free_pages_bulk
  in free_hot_cold_page (otherwise we would have to hold a page
  in a pageset during the period that the boot pagesets are in use).
- remove mistaken __cpuinitdata attribute and revert back to __initdata
  for the boot pageset. A boot pageset is not necessary for cpu hotplug.

Tested for UP SMP NUMA on x86_64 (2.6.12-rc6-mm1): UP SMP NUMA Tested on
IA64 (2.6.12-rc5-mm2): NUMA (2.6.12-rc6-mm1 broken for IA64 because of
sparsemem patches)

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 42 insertions, 66 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a95e72d7f945..418102a02921 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -71,11 +71,6 @@ EXPORT_SYMBOL(nr_swap_pages);
 struct zone *zone_table[1 << (ZONES_SHIFT + NODES_SHIFT)];
 EXPORT_SYMBOL(zone_table);
 
-#ifdef CONFIG_NUMA
-static struct per_cpu_pageset
-        pageset_table[MAX_NR_ZONES*MAX_NUMNODES*NR_CPUS] __initdata;
-#endif
-
 static char *zone_names[MAX_NR_ZONES] = { "DMA", "Normal", "HighMem" };
 int min_free_kbytes = 1024;
 
@@ -652,10 +647,10 @@ static void fastcall free_hot_cold_page(struct page *page, int cold)
         free_pages_check(__FUNCTION__, page);
         pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
         local_irq_save(flags);
-        if (pcp->count >= pcp->high)
-                pcp->count -= free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
         list_add(&page->lru, &pcp->list);
         pcp->count++;
+        if (pcp->count >= pcp->high)
+                pcp->count -= free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
         local_irq_restore(flags);
         put_cpu();
 }
@@ -1714,57 +1709,55 @@ static int __devinit zone_batchsize(struct zone *zone)
         return batch;
 }
 
+inline void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
+{
+        struct per_cpu_pages *pcp;
+
+        pcp = &p->pcp[0];               /* hot */
+        pcp->count = 0;
+        pcp->low = 2 * batch;
+        pcp->high = 6 * batch;
+        pcp->batch = max(1UL, 1 * batch);
+        INIT_LIST_HEAD(&pcp->list);
+
+        pcp = &p->pcp[1];               /* cold*/
+        pcp->count = 0;
+        pcp->low = 0;
+        pcp->high = 2 * batch;
+        pcp->batch = max(1UL, 1 * batch);
+        INIT_LIST_HEAD(&pcp->list);
+}
+
 #ifdef CONFIG_NUMA
 /*
- * Dynamicaly allocate memory for the
+ * Boot pageset table. One per cpu which is going to be used for all
+ * zones and all nodes. The parameters will be set in such a way
+ * that an item put on a list will immediately be handed over to
+ * the buddy list. This is safe since pageset manipulation is done
+ * with interrupts disabled.
+ *
+ * Some NUMA counter updates may also be caught by the boot pagesets.
+ * These will be discarded when bootup is complete.
+ */
+static struct per_cpu_pageset
+        boot_pageset[NR_CPUS] __initdata;
+
+/*
+ * Dynamically allocate memory for the
  * per cpu pageset array in struct zone.
  */
 static int __devinit process_zones(int cpu)
 {
         struct zone *zone, *dzone;
-        int i;
 
         for_each_zone(zone) {
-                struct per_cpu_pageset *npageset = NULL;
 
-                npageset = kmalloc_node(sizeof(struct per_cpu_pageset),
+                zone->pageset[cpu] = kmalloc_node(sizeof(struct per_cpu_pageset),
                                          GFP_KERNEL, cpu_to_node(cpu));
-                if (!npageset) {
-                        zone->pageset[cpu] = NULL;
+                if (!zone->pageset[cpu])
                         goto bad;
-                }
 
-                if (zone->pageset[cpu]) {
-                        memcpy(npageset, zone->pageset[cpu],
-                                        sizeof(struct per_cpu_pageset));
-
-                        /* Relocate lists */
-                        for (i = 0; i < 2; i++) {
-                                INIT_LIST_HEAD(&npageset->pcp[i].list);
-                                list_splice(&zone->pageset[cpu]->pcp[i].list,
-                                        &npageset->pcp[i].list);
-                        }
-                } else {
-                        struct per_cpu_pages *pcp;
-                        unsigned long batch;
-
-                        batch = zone_batchsize(zone);
-
-                        pcp = &npageset->pcp[0];                /* hot */
-                        pcp->count = 0;
-                        pcp->low = 2 * batch;
-                        pcp->high = 6 * batch;
-                        pcp->batch = 1 * batch;
-                        INIT_LIST_HEAD(&pcp->list);
-
-                        pcp = &npageset->pcp[1];                /* cold*/
-                        pcp->count = 0;
-                        pcp->low = 0;
-                        pcp->high = 2 * batch;
-                        pcp->batch = 1 * batch;
-                        INIT_LIST_HEAD(&pcp->list);
-                }
-                zone->pageset[cpu] = npageset;
+                setup_pageset(zone->pageset[cpu], zone_batchsize(zone));
         }
 
         return 0;
@@ -1878,30 +1871,13 @@ static void __init free_area_init_core(struct pglist_data *pgdat,
                 batch = zone_batchsize(zone);
 
                 for (cpu = 0; cpu < NR_CPUS; cpu++) {
-                        struct per_cpu_pages *pcp;
 #ifdef CONFIG_NUMA
-                        struct per_cpu_pageset *pgset;
-                        pgset = &pageset_table[nid*MAX_NR_ZONES*NR_CPUS +
-                                        (j * NR_CPUS) + cpu];
-
-                        zone->pageset[cpu] = pgset;
+                        /* Early boot. Slab allocator not functional yet */
+                        zone->pageset[cpu] = &boot_pageset[cpu];
+                        setup_pageset(&boot_pageset[cpu],0);
 #else
-                        struct per_cpu_pageset *pgset = zone_pcp(zone, cpu);
+                        setup_pageset(zone_pcp(zone,cpu), batch);
 #endif
-
-                        pcp = &pgset->pcp[0];                   /* hot */
-                        pcp->count = 0;
-                        pcp->low = 2 * batch;
-                        pcp->high = 6 * batch;
-                        pcp->batch = 1 * batch;
-                        INIT_LIST_HEAD(&pcp->list);
-
-                        pcp = &pgset->pcp[1];                   /* cold */
-                        pcp->count = 0;
-                        pcp->low = 0;
-                        pcp->high = 2 * batch;
-                        pcp->batch = 1 * batch;
-                        INIT_LIST_HEAD(&pcp->list);
                 }
                 printk(KERN_DEBUG "  %s zone: %lu pages, LIFO batch:%lu\n",
                                 zone_names[j], realsize, batch);