mm: compaction: cache if a pageblock was scanned and no pages were isolated

[karo-tx-linux.git] / mm / internal.h

diff --git a/mm/internal.h b/mm/internal.h
index 96cda4c6ac56762f69a919f7fe9332666be98930..f652660ab475e4e86a52d6108308c361b9830cd3 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -12,6 +12,7 @@
 #define __MM_INTERNAL_H
 
 #include <linux/mm.h>
+#include <linux/rmap.h>
 
 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
                unsigned long floor, unsigned long ceiling);
@@ -118,19 +119,14 @@ struct compact_control {
        unsigned long nr_freepages;     /* Number of isolated free pages */
        unsigned long nr_migratepages;  /* Number of pages to migrate */
        unsigned long free_pfn;         /* isolate_freepages search base */
-       unsigned long start_free_pfn;   /* where we started the search */
        unsigned long migrate_pfn;      /* isolate_migratepages search base */
        bool sync;                      /* Synchronous migration */
-       bool wrapped;                   /* Order > 0 compactions are
-                                          incremental, once free_pfn
-                                          and migrate_pfn meet, we restart
-                                          from the top of the zone;
-                                          remember we wrapped around. */
+       bool ignore_skip_hint;          /* Scan blocks even if marked skip */
 
        int order;                      /* order a direct compactor needs */
        int migratetype;                /* MOVABLE, RECLAIMABLE etc */
        struct zone *zone;
-       bool *contended;                /* True if a lock was contended */
+       bool contended;                 /* True if a lock was contended */
        struct page **page;             /* Page captured of requested size */
 };
 
@@ -372,4 +368,51 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone,
 #define ALLOC_CPUSET           0x40 /* check for correct cpuset */
 #define ALLOC_CMA              0x80 /* allow allocations from CMA areas */
 
+/*
+ * Unnecessary readahead harms performance, especially for SSD devices, where
+ * large reads are significantly more expensive than small ones.
+ * These implements simple swap random access detection. In swap page fault: if
+ * the page is found in swapcache, decrease a counter in the vma, otherwise we
+ * need to perform sync swapin and the counter is increased.  Optionally swapin
+ * will perform readahead if the counter is below a threshold.
+ */
+#ifdef CONFIG_SWAP
+#define SWAPRA_MISS_THRESHOLD  (100)
+#define SWAPRA_MAX_MISS ((SWAPRA_MISS_THRESHOLD) * 10)
+static inline void swap_cache_hit(struct vm_area_struct *vma)
+{
+       if (vma && vma->anon_vma)
+               atomic_dec_if_positive(&vma->anon_vma->swapra_miss);
+}
+
+static inline void swap_cache_miss(struct vm_area_struct *vma)
+{
+       if (!vma || !vma->anon_vma)
+               return;
+       if (atomic_read(&vma->anon_vma->swapra_miss) < SWAPRA_MAX_MISS)
+               atomic_inc(&vma->anon_vma->swapra_miss);
+}
+
+static inline int swap_cache_skip_readahead(struct vm_area_struct *vma)
+{
+       if (!vma || !vma->anon_vma)
+               return 0;
+       return atomic_read(&vma->anon_vma->swapra_miss) >
+               SWAPRA_MISS_THRESHOLD;
+}
+#else
+static inline void swap_cache_hit(struct vm_area_struct *vma)
+{
+}
+
+static inline void swap_cache_miss(struct vm_area_struct *vma)
+{
+}
+
+static inline int swap_cache_skip_readahead(struct vm_area_struct *vma)
+{
+       return 0;
+}
+#endif /* CONFIG_SWAP */
+
 #endif /* __MM_INTERNAL_H */