rculfhash: default mm type

[urcu.git] / rculfhash.c

diff --git a/rculfhash.c b/rculfhash.c
index 6c648f17da8a939d22894067eb1cc8c24620a8e0..5ef2c781e3f6330ca631910df85f0a8ef92de954 100644 (file)
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -1271,6 +1271,36 @@ struct cds_lfht *_cds_lfht_new(unsigned long init_size,
        if (!init_size || (init_size & (init_size - 1)))
                return NULL;
 
+       /*
+        * Memory management plugin default.
+        */
+       if (!mm) {
+               if (!max_nr_buckets) {
+                       /*
+                        * If the maximum number of buckets is not
+                        * specified, we cannot use the mmap allocator,
+                        * so fallback on order allocator.
+                        */
+                       mm = &cds_lfht_mm_order;
+               } else if (CAA_BITS_PER_LONG > 32
+                               && max_nr_buckets <= (1ULL << 32)) {
+                       /*
+                        * For 64-bit architectures, with max number of
+                        * buckets small enough not to use the entire
+                        * 64-bit memory mapping space (and allowing a
+                        * fair number of hash table instances), use the
+                        * mmap allocator, which is faster than the
+                        * order allocator.
+                        */
+                       mm = &cds_lfht_mm_mmap;
+               } else {
+                       /*
+                        * The fallback is to use the order allocator.
+                        */
+                       mm = &cds_lfht_mm_order;
+               }
+       }
+
        /* max_nr_buckets == 0 for order based mm means infinite */
        if (mm == &cds_lfht_mm_order && !max_nr_buckets)
                max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);