[PATCH 12/25] mm, page_alloc: Consider dirtyable memory in terms of nodes
From: Mel Gorman
Date: Mon Jun 08 2015 - 10:00:20 EST
Historically dirty pages were spread among zones but now that LRUs are
per-node it is more appropriate to consider dirty pages in a node.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
include/linux/mmzone.h | 12 +++----
include/linux/writeback.h | 2 +-
mm/page-writeback.c | 89 ++++++++++++++++++++++++++---------------------
mm/page_alloc.c | 8 +++--
4 files changed, 62 insertions(+), 49 deletions(-)
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 4c761809d151..22cdd8da6fb0 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -355,12 +355,6 @@ struct zone {
struct pglist_data *zone_pgdat;
struct per_cpu_pageset __percpu *pageset;
- /*
- * This is a per-zone reserve of pages that should not be
- * considered dirtyable memory.
- */
- unsigned long dirty_balance_reserve;
-
#ifndef CONFIG_SPARSEMEM
/*
* Flags for a pageblock_nr_pages block. See pageblock-flags.h.
@@ -760,6 +754,12 @@ typedef struct pglist_data {
/* Number of pages migrated during the rate limiting time interval */
unsigned long numabalancing_migrate_nr_pages;
#endif
+ /*
+ * This is a per-node reserve of pages that should not be
+ * considered dirtyable memory.
+ */
+ unsigned long dirty_balance_reserve;
+
/* Write-intensive fields used from the page allocator */
ZONE_PADDING(_pad1_)
spinlock_t lru_lock;
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index b2dd371ec0ca..76602a5d721e 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -119,7 +119,7 @@ void laptop_mode_timer_fn(unsigned long data);
static inline void laptop_sync_completion(void) { }
#endif
void throttle_vm_writeout(gfp_t gfp_mask);
-bool zone_dirty_ok(struct zone *zone);
+bool node_dirty_ok(struct pglist_data *pgdat);
extern unsigned long global_dirty_limit;
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 9707c450c7c5..88e346f36f79 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -174,21 +174,30 @@ static unsigned long writeout_period_time = 0;
*/
/**
- * zone_dirtyable_memory - number of dirtyable pages in a zone
- * @zone: the zone
+ * node_dirtyable_memory - number of dirtyable pages in a node
+ * @pgdat: the node
*
- * Returns the zone's number of pages potentially available for dirty
- * page cache. This is the base value for the per-zone dirty limits.
+ * Returns the node's number of pages potentially available for dirty
+ * page cache. This is the base value for the per-node dirty limits.
*/
-static unsigned long zone_dirtyable_memory(struct zone *zone)
+static unsigned long node_dirtyable_memory(struct pglist_data *pgdat)
{
- unsigned long nr_pages;
+ unsigned long nr_pages = 0;
+ int z;
- nr_pages = zone_page_state(zone, NR_FREE_PAGES);
- nr_pages -= min(nr_pages, zone->dirty_balance_reserve);
+ for (z = 0; z < MAX_NR_ZONES; z++) {
+ struct zone *zone = pgdat->node_zones + z;
- nr_pages += node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE);
- nr_pages += node_page_state(zone->zone_pgdat, NR_ACTIVE_FILE);
+ if (!populated_zone(zone))
+ continue;
+
+ nr_pages += zone_page_state(zone, NR_FREE_PAGES);
+ }
+
+ nr_pages -= min(nr_pages, pgdat->dirty_balance_reserve);
+
+ nr_pages += node_page_state(pgdat, NR_INACTIVE_FILE);
+ nr_pages += node_page_state(pgdat, NR_ACTIVE_FILE);
return nr_pages;
}
@@ -199,22 +208,11 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
int node;
unsigned long x = 0;
- for_each_node_state(node, N_HIGH_MEMORY) {
- struct zone *z = &NODE_DATA(node)->node_zones[ZONE_HIGHMEM];
-
- x += zone_dirtyable_memory(z);
- }
/*
- * Unreclaimable memory (kernel memory or anonymous memory
- * without swap) can bring down the dirtyable pages below
- * the zone's dirty balance reserve and the above calculation
- * will underflow. However we still want to add in nodes
- * which are below threshold (negative values) to get a more
- * accurate calculation but make sure that the total never
- * underflows.
+ * LRU lists are per-node so there is accurate way of accurately
+ * calculating dirtyable memory of just the high zone
*/
- if ((long)x < 0)
- x = 0;
+ x = totalhigh_pages;
/*
* Make sure that the number of highmem pages is never larger
@@ -289,23 +287,23 @@ void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty)
}
/**
- * zone_dirty_limit - maximum number of dirty pages allowed in a zone
- * @zone: the zone
+ * node_dirty_limit - maximum number of dirty pages allowed in a node
+ * @pgdat: the node
*
- * Returns the maximum number of dirty pages allowed in a zone, based
- * on the zone's dirtyable memory.
+ * Returns the maximum number of dirty pages allowed in a node, based
+ * on the node's dirtyable memory.
*/
-static unsigned long zone_dirty_limit(struct zone *zone)
+static unsigned long node_dirty_limit(struct pglist_data *pgdat)
{
- unsigned long zone_memory = zone_dirtyable_memory(zone);
+ unsigned long node_memory = node_dirtyable_memory(pgdat);
struct task_struct *tsk = current;
unsigned long dirty;
if (vm_dirty_bytes)
dirty = DIV_ROUND_UP(vm_dirty_bytes, PAGE_SIZE) *
- zone_memory / global_dirtyable_memory();
+ node_memory / global_dirtyable_memory();
else
- dirty = vm_dirty_ratio * zone_memory / 100;
+ dirty = vm_dirty_ratio * node_memory / 100;
if (tsk->flags & PF_LESS_THROTTLE || rt_task(tsk))
dirty += dirty / 4;
@@ -314,19 +312,30 @@ static unsigned long zone_dirty_limit(struct zone *zone)
}
/**
- * zone_dirty_ok - tells whether a zone is within its dirty limits
- * @zone: the zone to check
+ * node_dirty_ok - tells whether a node is within its dirty limits
+ * @pgdat: the node to check
*
- * Returns %true when the dirty pages in @zone are within the zone's
+ * Returns %true when the dirty pages in @pgdat are within the node's
* dirty limit, %false if the limit is exceeded.
*/
-bool zone_dirty_ok(struct zone *zone)
+bool node_dirty_ok(struct pglist_data *pgdat)
{
- unsigned long limit = zone_dirty_limit(zone);
+ int z;
+ unsigned long limit = node_dirty_limit(pgdat);
+ unsigned long nr_pages = 0;
+
+ for (z = 0; z < MAX_NR_ZONES; z++) {
+ struct zone *zone = pgdat->node_zones + z;
+
+ if (!populated_zone(zone))
+ continue;
+
+ nr_pages += zone_page_state(zone, NR_FILE_DIRTY);
+ nr_pages += zone_page_state(zone, NR_UNSTABLE_NFS);
+ nr_pages += zone_page_state(zone, NR_WRITEBACK);
+ }
- return zone_page_state(zone, NR_FILE_DIRTY) +
- zone_page_state(zone, NR_UNSTABLE_NFS) +
- zone_page_state(zone, NR_WRITEBACK) <= limit;
+ return nr_pages <= limit;
}
int dirty_background_ratio_handler(struct ctl_table *table, int write,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 34201c141916..fa54792f1719 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2042,6 +2042,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags,
(gfp_mask & __GFP_WRITE);
int nr_fair_skipped = 0;
bool zonelist_rescan;
+ struct pglist_data *last_pgdat = NULL;
zonelist_scan:
zonelist_rescan = false;
@@ -2101,8 +2102,11 @@ zonelist_scan:
* will require awareness of zones in the
* dirty-throttling and the flusher threads.
*/
- if (consider_zone_dirty && !zone_dirty_ok(zone))
+ if (consider_zone_dirty && last_pgdat != zone->zone_pgdat &&
+ !node_dirty_ok(zone->zone_pgdat)) {
continue;
+ }
+ last_pgdat = zone->zone_pgdat;
mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
if (!zone_watermark_ok(zone, order, mark,
@@ -5656,7 +5660,7 @@ static void calculate_totalreserve_pages(void)
* situation where reclaim has to clean pages
* in order to balance the zones.
*/
- zone->dirty_balance_reserve = max;
+ pgdat->dirty_balance_reserve += max;
}
}
dirty_balance_reserve = reserve_pages;
--
2.3.5
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