Page allocator: get rid of the list of cold pages
We have repeatedly discussed if the cold pages still have a point. There is
one way to join the two lists: Use a single list and put the cold pages at the
end and the hot pages at the beginning. That way a single list can serve for
both types of allocations.
The discussion of the RFC for this and Mel's measurements indicate that
there may not be too much of a point left to having separate lists for
hot and cold pages (see http://marc.info/?t=119492914200001&r=1&w=2).
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Martin Bligh <mbligh@mbligh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5c7de8e..144c0967 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -901,24 +901,21 @@
{
unsigned long flags;
struct zone *zone;
- int i;
for_each_zone(zone) {
struct per_cpu_pageset *pset;
+ struct per_cpu_pages *pcp;
if (!populated_zone(zone))
continue;
pset = zone_pcp(zone, cpu);
- for (i = 0; i < ARRAY_SIZE(pset->pcp); i++) {
- struct per_cpu_pages *pcp;
- pcp = &pset->pcp[i];
- local_irq_save(flags);
- free_pages_bulk(zone, pcp->count, &pcp->list, 0);
- pcp->count = 0;
- local_irq_restore(flags);
- }
+ pcp = &pset->pcp;
+ local_irq_save(flags);
+ free_pages_bulk(zone, pcp->count, &pcp->list, 0);
+ pcp->count = 0;
+ local_irq_restore(flags);
}
}
@@ -993,10 +990,13 @@
arch_free_page(page, 0);
kernel_map_pages(page, 1, 0);
- pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
+ pcp = &zone_pcp(zone, get_cpu())->pcp;
local_irq_save(flags);
__count_vm_event(PGFREE);
- list_add(&page->lru, &pcp->list);
+ if (cold)
+ list_add_tail(&page->lru, &pcp->list);
+ else
+ list_add(&page->lru, &pcp->list);
set_page_private(page, get_pageblock_migratetype(page));
pcp->count++;
if (pcp->count >= pcp->high) {
@@ -1054,7 +1054,7 @@
if (likely(order == 0)) {
struct per_cpu_pages *pcp;
- pcp = &zone_pcp(zone, cpu)->pcp[cold];
+ pcp = &zone_pcp(zone, cpu)->pcp;
local_irq_save(flags);
if (!pcp->count) {
pcp->count = rmqueue_bulk(zone, 0,
@@ -1064,9 +1064,15 @@
}
/* Find a page of the appropriate migrate type */
- list_for_each_entry(page, &pcp->list, lru)
- if (page_private(page) == migratetype)
- break;
+ if (cold) {
+ list_for_each_entry_reverse(page, &pcp->list, lru)
+ if (page_private(page) == migratetype)
+ break;
+ } else {
+ list_for_each_entry(page, &pcp->list, lru)
+ if (page_private(page) == migratetype)
+ break;
+ }
/* Allocate more to the pcp list if necessary */
if (unlikely(&page->lru == &pcp->list)) {
@@ -1793,12 +1799,9 @@
pageset = zone_pcp(zone, cpu);
- printk("CPU %4d: Hot: hi:%5d, btch:%4d usd:%4d "
- "Cold: hi:%5d, btch:%4d usd:%4d\n",
- cpu, pageset->pcp[0].high,
- pageset->pcp[0].batch, pageset->pcp[0].count,
- pageset->pcp[1].high, pageset->pcp[1].batch,
- pageset->pcp[1].count);
+ printk("CPU %4d: hi:%5d, btch:%4d usd:%4d\n",
+ cpu, pageset->pcp.high,
+ pageset->pcp.batch, pageset->pcp.count);
}
}
@@ -2596,17 +2599,11 @@
memset(p, 0, sizeof(*p));
- pcp = &p->pcp[0]; /* hot */
+ pcp = &p->pcp;
pcp->count = 0;
pcp->high = 6 * batch;
pcp->batch = max(1UL, 1 * batch);
INIT_LIST_HEAD(&pcp->list);
-
- pcp = &p->pcp[1]; /* cold*/
- pcp->count = 0;
- pcp->high = 2 * batch;
- pcp->batch = max(1UL, batch/2);
- INIT_LIST_HEAD(&pcp->list);
}
/*
@@ -2619,7 +2616,7 @@
{
struct per_cpu_pages *pcp;
- pcp = &p->pcp[0]; /* hot list */
+ pcp = &p->pcp;
pcp->high = high;
pcp->batch = max(1UL, high/4);
if ((high/4) > (PAGE_SHIFT * 8))
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 9ffc573..888668e 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -337,7 +337,7 @@
* Check if there are pages remaining in this pageset
* if not then there is nothing to expire.
*/
- if (!p->expire || (!p->pcp[0].count && !p->pcp[1].count))
+ if (!p->expire || !p->pcp.count)
continue;
/*
@@ -352,11 +352,8 @@
if (p->expire)
continue;
- if (p->pcp[0].count)
- drain_zone_pages(zone, p->pcp + 0);
-
- if (p->pcp[1].count)
- drain_zone_pages(zone, p->pcp + 1);
+ if (p->pcp.count)
+ drain_zone_pages(zone, &p->pcp);
#endif
}
@@ -693,20 +690,17 @@
"\n pagesets");
for_each_online_cpu(i) {
struct per_cpu_pageset *pageset;
- int j;
pageset = zone_pcp(zone, i);
- for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
- seq_printf(m,
- "\n cpu: %i pcp: %i"
- "\n count: %i"
- "\n high: %i"
- "\n batch: %i",
- i, j,
- pageset->pcp[j].count,
- pageset->pcp[j].high,
- pageset->pcp[j].batch);
- }
+ seq_printf(m,
+ "\n cpu: %i"
+ "\n count: %i"
+ "\n high: %i"
+ "\n batch: %i",
+ i,
+ pageset->pcp.count,
+ pageset->pcp.high,
+ pageset->pcp.batch);
#ifdef CONFIG_SMP
seq_printf(m, "\n vm stats threshold: %d",
pageset->stat_threshold);