Merge remote-tracking branch 'asoc/fix/dma' into asoc-linus

[cascardo/linux.git] / include / linux / shrinker.h

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index ac6b8ee..68c0970 100644 (file)
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -4,39 +4,67 @@
 /*
  * This struct is used to pass information from page reclaim to the shrinkers.
  * We consolidate the values for easier extention later.
+ *
+ * The 'gfpmask' refers to the allocation we are currently trying to
+ * fulfil.
  */
 struct shrink_control {
        gfp_t gfp_mask;
 
-       /* How many slab objects shrinker() should scan and try to reclaim */
+       /*
+        * How many objects scan_objects should scan and try to reclaim.
+        * This is reset before every call, so it is safe for callees
+        * to modify.
+        */
        unsigned long nr_to_scan;
+
+       /* shrink from these nodes */
+       nodemask_t nodes_to_scan;
+       /* current node being shrunk (for NUMA aware shrinkers) */
+       int nid;
 };
 
+#define SHRINK_STOP (~0UL)
 /*
  * A callback you can register to apply pressure to ageable caches.
  *
- * 'sc' is passed shrink_control which includes a count 'nr_to_scan'
- * and a 'gfpmask'.  It should look through the least-recently-used
- * 'nr_to_scan' entries and attempt to free them up.  It should return
- * the number of objects which remain in the cache.  If it returns -1, it means
- * it cannot do any scanning at this time (eg. there is a risk of deadlock).
+ * @count_objects should return the number of freeable items in the cache. If
+ * there are no objects to free or the number of freeable items cannot be
+ * determined, it should return 0. No deadlock checks should be done during the
+ * count callback - the shrinker relies on aggregating scan counts that couldn't
+ * be executed due to potential deadlocks to be run at a later call when the
+ * deadlock condition is no longer pending.
  *
- * The 'gfpmask' refers to the allocation we are currently trying to
- * fulfil.
+ * @scan_objects will only be called if @count_objects returned a non-zero
+ * value for the number of freeable objects. The callout should scan the cache
+ * and attempt to free items from the cache. It should then return the number
+ * of objects freed during the scan, or SHRINK_STOP if progress cannot be made
+ * due to potential deadlocks. If SHRINK_STOP is returned, then no further
+ * attempts to call the @scan_objects will be made from the current reclaim
+ * context.
  *
- * Note that 'shrink' will be passed nr_to_scan == 0 when the VM is
- * querying the cache size, so a fastpath for that case is appropriate.
+ * @flags determine the shrinker abilities, like numa awareness
  */
 struct shrinker {
-       int (*shrink)(struct shrinker *, struct shrink_control *sc);
+       unsigned long (*count_objects)(struct shrinker *,
+                                      struct shrink_control *sc);
+       unsigned long (*scan_objects)(struct shrinker *,
+                                     struct shrink_control *sc);
+
        int seeks;      /* seeks to recreate an obj */
        long batch;     /* reclaim batch size, 0 = default */
+       unsigned long flags;
 
        /* These are for internal use */
        struct list_head list;
-       atomic_long_t nr_in_batch; /* objs pending delete */
+       /* objs pending delete, per node */
+       atomic_long_t *nr_deferred;
 };
 #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */
-extern void register_shrinker(struct shrinker *);
+
+/* Flags */
+#define SHRINKER_NUMA_AWARE (1 << 0)
+
+extern int register_shrinker(struct shrinker *);
 extern void unregister_shrinker(struct shrinker *);
 #endif