[PATCH 3/8] Split the per-cpu lists into kernel and user parts
From: Mel Gorman
Date: Thu Sep 07 2006 - 15:02:21 EST
The freelists for each allocation type can slowly become fragmented due to
the per-cpu list. Consider what happens when the following happens
1. A 2^(MAX_ORDER-1) list is reserved for __GFP_EASYRCLM pages
2. An order-0 page is allocated from the newly reserved block
3. The page is freed and placed on the per-cpu list
4. alloc_page() is called with GFP_KERNEL as the gfp_mask
5. The per-cpu list is used to satisfy the allocation
This results in a kernel page is in the middle of a RCLM_EASY region. This
means that over long periods of the time, the anti-fragmentation scheme
slowly degrades to the standard allocator.
This patch divides the per-cpu lists into RCLM_TYPES number of lists.
Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
Signed-off-by: Joel Schopp <jschopp@xxxxxxxxxxxxxx>
---
include/linux/mmzone.h | 16 +++++++++--
mm/page_alloc.c | 63 +++++++++++++++++++++++++++-----------------
mm/vmstat.c | 4 +-
3 files changed, 56 insertions(+), 27 deletions(-)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.18-rc5-mm1-002_fragcore/include/linux/mmzone.h linux-2.6.18-rc5-mm1-003_percpu/include/linux/mmzone.h
--- linux-2.6.18-rc5-mm1-002_fragcore/include/linux/mmzone.h 2006-09-04 18:37:59.000000000 +0100
+++ linux-2.6.18-rc5-mm1-003_percpu/include/linux/mmzone.h 2006-09-04 18:39:39.000000000 +0100
@@ -28,6 +28,8 @@
#define RCLM_EASY 1
#define RCLM_TYPES 2
+#define for_each_rclmtype(type) \
+ for (type = 0; type < RCLM_TYPES; type++)
#define for_each_rclmtype_order(type, order) \
for (order = 0; order < MAX_ORDER; order++) \
for (type = 0; type < RCLM_TYPES; type++)
@@ -77,10 +79,10 @@ enum zone_stat_item {
NR_VM_ZONE_STAT_ITEMS };
struct per_cpu_pages {
- int count; /* number of pages in the list */
+ int counts[RCLM_TYPES]; /* number of pages in the list */
int high; /* high watermark, emptying needed */
int batch; /* chunk size for buddy add/remove */
- struct list_head list; /* the list of pages */
+ struct list_head list[RCLM_TYPES]; /* the list of pages */
};
struct per_cpu_pageset {
@@ -91,6 +93,16 @@ struct per_cpu_pageset {
#endif
} ____cacheline_aligned_in_smp;
+static inline int pcp_count(struct per_cpu_pages *pcp)
+{
+ int rclmtype, count = 0;
+
+ for_each_rclmtype(rclmtype)
+ count += pcp->counts[rclmtype];
+
+ return count;
+}
+
#ifdef CONFIG_NUMA
#define zone_pcp(__z, __cpu) ((__z)->pageset[(__cpu)])
#else
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.18-rc5-mm1-002_fragcore/mm/page_alloc.c linux-2.6.18-rc5-mm1-003_percpu/mm/page_alloc.c
--- linux-2.6.18-rc5-mm1-002_fragcore/mm/page_alloc.c 2006-09-04 18:37:59.000000000 +0100
+++ linux-2.6.18-rc5-mm1-003_percpu/mm/page_alloc.c 2006-09-04 18:39:39.000000000 +0100
@@ -745,7 +745,7 @@ static int rmqueue_bulk(struct zone *zon
*/
void drain_node_pages(int nodeid)
{
- int i;
+ int i, pindex;
enum zone_type z;
unsigned long flags;
@@ -761,10 +761,14 @@ void drain_node_pages(int nodeid)
struct per_cpu_pages *pcp;
pcp = &pset->pcp[i];
- if (pcp->count) {
+ if (pcp_count(pcp)) {
local_irq_save(flags);
- free_pages_bulk(zone, pcp->count, &pcp->list, 0);
- pcp->count = 0;
+ for_each_rclmtype(pindex) {
+ free_pages_bulk(zone,
+ pcp->counts[pindex],
+ &pcp->list[pindex], 0);
+ pcp->counts[pindex] = 0;
+ }
local_irq_restore(flags);
}
}
@@ -777,7 +781,7 @@ static void __drain_pages(unsigned int c
{
unsigned long flags;
struct zone *zone;
- int i;
+ int i, pindex;
for_each_zone(zone) {
struct per_cpu_pageset *pset;
@@ -788,8 +792,13 @@ static void __drain_pages(unsigned int c
pcp = &pset->pcp[i];
local_irq_save(flags);
- free_pages_bulk(zone, pcp->count, &pcp->list, 0);
- pcp->count = 0;
+ for_each_rclmtype(pindex) {
+ free_pages_bulk(zone,
+ pcp->counts[pindex],
+ &pcp->list[pindex], 0);
+
+ pcp->counts[pindex] = 0;
+ }
local_irq_restore(flags);
}
}
@@ -851,6 +860,7 @@ void drain_local_pages(void)
static void fastcall free_hot_cold_page(struct page *page, int cold)
{
struct zone *zone = page_zone(page);
+ int pindex = get_pageblock_type(page);
struct per_cpu_pages *pcp;
unsigned long flags;
@@ -866,11 +876,11 @@ static void fastcall free_hot_cold_page(
pcp = &zone_pcp(zone, get_cpu())->pcp[cold];
local_irq_save(flags);
__count_vm_event(PGFREE);
- list_add(&page->lru, &pcp->list);
- pcp->count++;
- if (pcp->count >= pcp->high) {
- free_pages_bulk(zone, pcp->batch, &pcp->list, 0);
- pcp->count -= pcp->batch;
+ list_add(&page->lru, &pcp->list[pindex]);
+ pcp->counts[pindex]++;
+ if (pcp->counts[pindex] >= pcp->high) {
+ free_pages_bulk(zone, pcp->batch, &pcp->list[pindex], 0);
+ pcp->counts[pindex] -= pcp->batch;
}
local_irq_restore(flags);
put_cpu();
@@ -916,6 +926,7 @@ static struct page *buffered_rmqueue(str
struct page *page;
int cold = !!(gfp_flags & __GFP_COLD);
int cpu;
+ int rclmtype = gfpflags_to_rclmtype(gfp_flags);
again:
cpu = get_cpu();
@@ -924,15 +935,15 @@ again:
pcp = &zone_pcp(zone, cpu)->pcp[cold];
local_irq_save(flags);
- if (!pcp->count) {
- pcp->count += rmqueue_bulk(zone, 0,
- pcp->batch, &pcp->list, gfp_flags);
- if (unlikely(!pcp->count))
+ if (!pcp->counts[rclmtype]) {
+ pcp->counts[rclmtype] += rmqueue_bulk(zone, 0,
+ pcp->batch, &pcp->list[rclmtype], gfp_flags);
+ if (unlikely(!pcp->counts[rclmtype]))
goto failed;
}
- page = list_entry(pcp->list.next, struct page, lru);
+ page = list_entry(pcp->list[rclmtype].next, struct page, lru);
list_del(&page->lru);
- pcp->count--;
+ pcp->counts[rclmtype]--;
} else {
spin_lock_irqsave(&zone->lock, flags);
page = __rmqueue(zone, order, gfp_flags);
@@ -1480,7 +1491,7 @@ void show_free_areas(void)
temperature ? "cold" : "hot",
pageset->pcp[temperature].high,
pageset->pcp[temperature].batch,
- pageset->pcp[temperature].count);
+ pcp_count(&pageset->pcp[temperature]));
}
}
@@ -1921,20 +1932,26 @@ static int __cpuinit zone_batchsize(stru
inline void setup_pageset(struct per_cpu_pageset *p, unsigned long batch)
{
struct per_cpu_pages *pcp;
+ int rclmtype;
memset(p, 0, sizeof(*p));
pcp = &p->pcp[0]; /* hot */
- pcp->count = 0;
+ for_each_rclmtype(rclmtype) {
+ pcp->counts[rclmtype] = 0;
+ INIT_LIST_HEAD(&pcp->list[rclmtype]);
+ }
pcp->high = 6 * batch;
pcp->batch = max(1UL, 1 * batch);
- INIT_LIST_HEAD(&pcp->list);
+ INIT_LIST_HEAD(&pcp->list[RCLM_EASY]);
pcp = &p->pcp[1]; /* cold*/
- pcp->count = 0;
+ for_each_rclmtype(rclmtype) {
+ pcp->counts[rclmtype] = 0;
+ INIT_LIST_HEAD(&pcp->list[rclmtype]);
+ }
pcp->high = 2 * batch;
pcp->batch = max(1UL, batch/2);
- INIT_LIST_HEAD(&pcp->list);
}
/*
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.18-rc5-mm1-002_fragcore/mm/vmstat.c linux-2.6.18-rc5-mm1-003_percpu/mm/vmstat.c
--- linux-2.6.18-rc5-mm1-002_fragcore/mm/vmstat.c 2006-09-04 18:34:33.000000000 +0100
+++ linux-2.6.18-rc5-mm1-003_percpu/mm/vmstat.c 2006-09-04 18:39:39.000000000 +0100
@@ -562,7 +562,7 @@ static int zoneinfo_show(struct seq_file
pageset = zone_pcp(zone, i);
for (j = 0; j < ARRAY_SIZE(pageset->pcp); j++) {
- if (pageset->pcp[j].count)
+ if (pcp_count(&pageset->pcp[j]))
break;
}
if (j == ARRAY_SIZE(pageset->pcp))
@@ -574,7 +574,7 @@ static int zoneinfo_show(struct seq_file
"\n high: %i"
"\n batch: %i",
i, j,
- pageset->pcp[j].count,
+ pcp_count(&pageset->pcp[j]),
pageset->pcp[j].high,
pageset->pcp[j].batch);
}
-
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