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authorMel Gorman <mgorman@techsingularity.net>2016-07-29 01:47:05 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-29 02:07:41 +0300
commitbca6759258dbef378bcf5b872177bcd2259ceb68 (patch)
tree17b2a1307ab70e4fb6f8f2cf4b535240b2433d5d /include
parente2ecc8a79ed49f7838b4fdf352c4c48cec9424ac (diff)
downloadlinux-bca6759258dbef378bcf5b872177bcd2259ceb68.tar.xz
mm, vmstat: remove zone and node double accounting by approximating retries
The number of LRU pages, dirty pages and writeback pages must be accounted for on both zones and nodes because of the reclaim retry logic, compaction retry logic and highmem calculations all depending on per-zone stats. Many lowmem allocations are immune from OOM kill due to a check in __alloc_pages_may_oom for (ac->high_zoneidx < ZONE_NORMAL) since commit 03668b3ceb0c ("oom: avoid oom killer for lowmem allocations"). The exception is costly high-order allocations or allocations that cannot fail. If the __alloc_pages_may_oom avoids OOM-kill for low-order lowmem allocations then it would fall through to __alloc_pages_direct_compact. This patch will blindly retry reclaim for zone-constrained allocations in should_reclaim_retry up to MAX_RECLAIM_RETRIES. This is not ideal but without per-zone stats there are not many alternatives. The impact it that zone-constrained allocations may delay before considering the OOM killer. As there is no guarantee enough memory can ever be freed to satisfy compaction, this patch avoids retrying compaction for zone-contrained allocations. In combination, that means that the per-node stats can be used when deciding whether to continue reclaim using a rough approximation. While it is possible this will make the wrong decision on occasion, it will not infinite loop as the number of reclaim attempts is capped by MAX_RECLAIM_RETRIES. The final step is calculating the number of dirtyable highmem pages. As those calculations only care about the global count of file pages in highmem. This patch uses a global counter used instead of per-zone stats as it is sufficient. In combination, this allows the per-zone LRU and dirty state counters to be removed. [mgorman@techsingularity.net: fix acct_highmem_file_pages()] Link: http://lkml.kernel.org/r/1468853426-12858-4-git-send-email-mgorman@techsingularity.netLink: http://lkml.kernel.org/r/1467970510-21195-35-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Suggested by: Michal Hocko <mhocko@kernel.org> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/mm_inline.h20
-rw-r--r--include/linux/mmzone.h4
-rw-r--r--include/linux/swap.h1
3 files changed, 17 insertions, 8 deletions
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index 9aadcc781857..dd22b08c47be 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -4,6 +4,22 @@
#include <linux/huge_mm.h>
#include <linux/swap.h>
+#ifdef CONFIG_HIGHMEM
+extern atomic_t highmem_file_pages;
+
+static inline void acct_highmem_file_pages(int zid, enum lru_list lru,
+ int nr_pages)
+{
+ if (is_highmem_idx(zid) && is_file_lru(lru))
+ atomic_add(nr_pages, &highmem_file_pages);
+}
+#else
+static inline void acct_highmem_file_pages(int zid, enum lru_list lru,
+ int nr_pages)
+{
+}
+#endif
+
/**
* page_is_file_cache - should the page be on a file LRU or anon LRU?
* @page: the page to test
@@ -29,9 +45,7 @@ static __always_inline void __update_lru_size(struct lruvec *lruvec,
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
__mod_node_page_state(pgdat, NR_LRU_BASE + lru, nr_pages);
- __mod_zone_page_state(&pgdat->node_zones[zid],
- NR_ZONE_LRU_BASE + !!is_file_lru(lru),
- nr_pages);
+ acct_highmem_file_pages(zid, lru, nr_pages);
}
static __always_inline void update_lru_size(struct lruvec *lruvec,
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index bd33e6f1bed0..a3b7f45aac56 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -110,10 +110,6 @@ struct zone_padding {
enum zone_stat_item {
/* First 128 byte cacheline (assuming 64 bit words) */
NR_FREE_PAGES,
- NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
- NR_ZONE_LRU_ANON = NR_ZONE_LRU_BASE,
- NR_ZONE_LRU_FILE,
- NR_ZONE_WRITE_PENDING, /* Count of dirty, writeback and unstable pages */
NR_MLOCK, /* mlock()ed pages found and moved off LRU */
NR_SLAB_RECLAIMABLE,
NR_SLAB_UNRECLAIMABLE,
diff --git a/include/linux/swap.h b/include/linux/swap.h
index b17cc4830fa6..cc753c639e3d 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -307,7 +307,6 @@ extern void lru_cache_add_active_or_unevictable(struct page *page,
struct vm_area_struct *vma);
/* linux/mm/vmscan.c */
-extern unsigned long zone_reclaimable_pages(struct zone *zone);
extern unsigned long pgdat_reclaimable_pages(struct pglist_data *pgdat);
extern unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
gfp_t gfp_mask, nodemask_t *mask);