mm, page_alloc: consider dirtyable memory in terms of nodes

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.

Link: http://lkml.kernel.org/r/1467970510-21195-17-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 62f477d6cfe86c5f804e17611809c5c01dbb37d1..fae2fe3c6942f98f4fe5fff7ed83685b2d893780 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -363,12 +363,6 @@ struct zone {
        struct pglist_data      *zone_pgdat;
        struct per_cpu_pageset __percpu *pageset;
 
-       /*
-        * This is a per-zone reserve of pages that are not available
-        * to userspace allocations.
-        */
-       unsigned long           totalreserve_pages;
-
 #ifndef CONFIG_SPARSEMEM
        /*
         * Flags for a pageblock_nr_pages block. See pageblock-flags.h.
@@ -687,6 +681,12 @@ 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 are not available
+        * to userspace allocations.
+        */
+       unsigned long           totalreserve_pages;
+
        /* Write-intensive fields used by page reclaim */
        ZONE_PADDING(_pad1_)
        spinlock_t              lru_lock;

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 717e6149e753364084698d3b32b1004d4087a281..fc1e16c25a296877e85d37d267bd953929ee93cd 100644 (file)
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -320,7 +320,7 @@ 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);
 int wb_domain_init(struct wb_domain *dom, gfp_t gfp);
 #ifdef CONFIG_CGROUP_WRITEBACK
 void wb_domain_exit(struct wb_domain *dom);

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 0ada2b2954b058585214f5f03a9e18829348b04f..f7c0fb993fb992c2f04bc6e80fa75be0c6043ed2 100644 (file)
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -267,26 +267,35 @@ static void wb_min_max_ratio(struct bdi_writeback *wb,
  */
 
 /**
- * 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;
+
+       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_FREE_PAGES);
+       }
 
-       nr_pages = zone_page_state(zone, NR_FREE_PAGES);
        /*
         * Pages reserved for the kernel should not be considered
         * dirtyable, to prevent a situation where reclaim has to
         * clean pages in order to balance the zones.
         */
-       nr_pages -= min(nr_pages, zone->totalreserve_pages);
+       nr_pages -= min(nr_pages, pgdat->totalreserve_pages);
 
-       nr_pages += node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE);
-       nr_pages += node_page_state(zone->zone_pgdat, NR_ACTIVE_FILE);
+       nr_pages += node_page_state(pgdat, NR_INACTIVE_FILE);
+       nr_pages += node_page_state(pgdat, NR_ACTIVE_FILE);
 
        return nr_pages;
 }
@@ -299,13 +308,24 @@ static unsigned long highmem_dirtyable_memory(unsigned long total)
        int i;
 
        for_each_node_state(node, N_HIGH_MEMORY) {
-               for (i = 0; i < MAX_NR_ZONES; i++) {
-                       struct zone *z = &NODE_DATA(node)->node_zones[i];
+               for (i = ZONE_NORMAL + 1; i < MAX_NR_ZONES; i++) {
+                       struct zone *z;
+                       unsigned long dirtyable;
+
+                       if (!is_highmem_idx(i))
+                               continue;
+
+                       z = &NODE_DATA(node)->node_zones[i];
+                       dirtyable = zone_page_state(z, NR_FREE_PAGES) +
+                               zone_page_state(z, NR_ZONE_LRU_FILE);
 
-                       if (is_highmem(z))
-                               x += zone_dirtyable_memory(z);
+                       /* watch for underflows */
+                       dirtyable -= min(dirtyable, high_wmark_pages(z));
+
+                       x += dirtyable;
                }
        }
+
        /*
         * Unreclaimable memory (kernel memory or anonymous memory
         * without swap) can bring down the dirtyable pages below
@@ -445,23 +465,23 @@ 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;
@@ -470,19 +490,30 @@ 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 749b3c358ead8ec68769447afd544d22bda672e7..73b018df6e4226a4d34ad882cf434e12fccffe8b 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2912,31 +2912,24 @@ zonelist_scan:
                }
                /*
                 * When allocating a page cache page for writing, we
-                * want to get it from a zone that is within its dirty
-                * limit, such that no single zone holds more than its
+                * want to get it from a node that is within its dirty
+                * limit, such that no single node holds more than its
                 * proportional share of globally allowed dirty pages.
-                * The dirty limits take into account the zone's
+                * The dirty limits take into account the node's
                 * lowmem reserves and high watermark so that kswapd
                 * should be able to balance it without having to
                 * write pages from its LRU list.
                 *
-                * This may look like it could increase pressure on
-                * lower zones by failing allocations in higher zones
-                * before they are full.  But the pages that do spill
-                * over are limited as the lower zones are protected
-                * by this very same mechanism.  It should not become
-                * a practical burden to them.
-                *
                 * XXX: For now, allow allocations to potentially
-                * exceed the per-zone dirty limit in the slowpath
+                * exceed the per-node dirty limit in the slowpath
                 * (spread_dirty_pages unset) before going into reclaim,
                 * which is important when on a NUMA setup the allowed
-                * zones are together not big enough to reach the
+                * nodes are together not big enough to reach the
                 * global limit.  The proper fix for these situations
-                * will require awareness of zones in the
+                * will require awareness of nodes in the
                 * dirty-throttling and the flusher threads.
                 */
-               if (ac->spread_dirty_pages && !zone_dirty_ok(zone))
+               if (ac->spread_dirty_pages && !node_dirty_ok(zone->zone_pgdat))
                        continue;
 
                mark = zone->watermark[alloc_flags & ALLOC_WMARK_MASK];
@@ -6701,6 +6694,9 @@ static void calculate_totalreserve_pages(void)
        enum zone_type i, j;
 
        for_each_online_pgdat(pgdat) {
+
+               pgdat->totalreserve_pages = 0;
+
                for (i = 0; i < MAX_NR_ZONES; i++) {
                        struct zone *zone = pgdat->node_zones + i;
                        long max = 0;
@@ -6717,7 +6713,7 @@ static void calculate_totalreserve_pages(void)
                        if (max > zone->managed_pages)
                                max = zone->managed_pages;
 
-                       zone->totalreserve_pages = max;
+                       pgdat->totalreserve_pages += max;
 
                        reserve_pages += max;
                }