add rculfhash-mm-chunk.c memory management

[ Edit by Mathieu Desnoyers: Update comment above
  struct cds_lfht_node *tbl_chunk. ]

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/Makefile.am b/Makefile.am
index 4d3f7bda75854cb4f219ff9ddb8246f18a276618..853ecd54c794b7fa4f0cfd1275d287d0ac1bfc1c 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -35,7 +35,7 @@ if COMPAT_FUTEX
 COMPAT+=compat_futex.c
 endif
 
-RCULFHASH=rculfhash.c rculfhash-mm-order.c
+RCULFHASH=rculfhash.c rculfhash-mm-order.c rculfhash-mm-chunk.c
 
 lib_LTLIBRARIES = liburcu-common.la \
                liburcu.la liburcu-qsbr.la \

diff --git a/rculfhash-internal.h b/rculfhash-internal.h
index 820e62c2ba6cda664c72b591b489831e12284353..f7c659044acceb36829c424ca594d3f3aed1f02d 100644 (file)
--- a/rculfhash-internal.h
+++ b/rculfhash-internal.h
@@ -38,6 +38,8 @@
 #define MAX_TABLE_ORDER                        64
 #endif
 
+#define MAX_CHUNK_TABLE                        (1UL << 10)
+
 #ifndef min
 #define min(a, b)      ((a) < (b) ? (a) : (b))
 #endif
@@ -94,6 +96,18 @@ struct cds_lfht {
                 * levels to improve cache locality for small index orders.
                 */
                struct cds_lfht_node *tbl_order[MAX_TABLE_ORDER];
+
+               /*
+                * Contains the bucket node chunks. The size of each
+                * bucket node chunk is ->min_alloc_size (we avoid to
+                * allocate chunks with different size). Chunks improve
+                * cache locality for small index orders, and are more
+                * friendly with environments where allocation of large
+                * contiguous memory areas is challenging due to memory
+                * fragmentation concerns or inability to use virtual
+                * memory addressing.
+                */
+               struct cds_lfht_node *tbl_chunk[0];
        };
 };
 

diff --git a/rculfhash-mm-chunk.c b/rculfhash-mm-chunk.c
new file mode 100644 (file)
index 0000000..0469776
--- /dev/null
+++ b/rculfhash-mm-chunk.c
@@ -0,0 +1,107 @@
+/*
+ * rculfhash-mm-chunk.c
+ *
+ * Chunk based memory management for Lock-Free RCU Hash Table
+ *
+ * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stddef.h>
+#include <rculfhash-internal.h>
+
+static
+void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
+{
+       if (order == 0) {
+               ht->tbl_chunk[0] = calloc(ht->min_nr_alloc_buckets,
+                       sizeof(struct cds_lfht_node));
+               assert(ht->tbl_chunk[0]);
+       } else if (order > ht->min_alloc_buckets_order) {
+               unsigned long i, len = 1UL << (order - 1 - ht->min_alloc_buckets_order);
+
+               for (i = len; i < 2 * len; i++) {
+                       ht->tbl_chunk[i] = calloc(ht->min_nr_alloc_buckets,
+                               sizeof(struct cds_lfht_node));
+                       assert(ht->tbl_chunk[i]);
+               }
+       }
+       /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
+}
+
+/*
+ * cds_lfht_free_bucket_table() should be called with decreasing order.
+ * When cds_lfht_free_bucket_table(0) is called, it means the whole
+ * lfht is destroyed.
+ */
+static
+void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
+{
+       if (order == 0)
+               poison_free(ht->tbl_chunk[0]);
+       else if (order > ht->min_alloc_buckets_order) {
+               unsigned long i, len = 1UL << (order - 1 - ht->min_alloc_buckets_order);
+
+               for (i = len; i < 2 * len; i++)
+                       poison_free(ht->tbl_chunk[i]);
+       }
+       /* Nothing to do for 0 < order && order <= ht->min_alloc_buckets_order */
+}
+
+static
+struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
+{
+       unsigned long chunk, offset;
+
+       chunk = index >> ht->min_alloc_buckets_order;
+       offset = index & (ht->min_nr_alloc_buckets - 1);
+       return &ht->tbl_chunk[chunk][offset];
+}
+
+static
+struct cds_lfht *alloc_cds_lfht(unsigned long min_nr_alloc_buckets,
+               unsigned long max_nr_buckets)
+{
+       struct cds_lfht *ht;
+       unsigned long nr_chunks, cds_lfht_size;
+
+       min_nr_alloc_buckets = max(min_nr_alloc_buckets,
+                       max_nr_buckets / MAX_CHUNK_TABLE);
+
+       nr_chunks = max_nr_buckets / min_nr_alloc_buckets;
+       cds_lfht_size = offsetof(struct cds_lfht, tbl_chunk) +
+                       sizeof(ht->tbl_chunk[0]) * nr_chunks;
+       cds_lfht_size = max(cds_lfht_size, sizeof(struct cds_lfht));
+       ht = calloc(1, cds_lfht_size);
+       assert(ht);
+
+       ht->mm = &cds_lfht_mm_chunk;
+
+       ht->min_nr_alloc_buckets = min_nr_alloc_buckets;
+       ht->min_alloc_buckets_order = get_count_order_ulong(min_nr_alloc_buckets);
+       ht->max_nr_buckets = max_nr_buckets;
+
+       ht->bucket_at = bucket_at;
+
+       return ht;
+}
+
+const struct cds_lfht_mm_type cds_lfht_mm_chunk = {
+       .alloc_cds_lfht = alloc_cds_lfht,
+       .alloc_bucket_table = cds_lfht_alloc_bucket_table,
+       .free_bucket_table = cds_lfht_free_bucket_table,
+       .bucket_at = bucket_at,
+};

diff --git a/urcu/rculfhash.h b/urcu/rculfhash.h
index c03baf41a2b8405fda996ddb633a250a8bcdd89a..1224ea808484fa385c5c5c3c92b8fbcfb113b52e 100644 (file)
--- a/urcu/rculfhash.h
+++ b/urcu/rculfhash.h
@@ -105,6 +105,7 @@ struct cds_lfht_mm_type {
 };
 
 extern const struct cds_lfht_mm_type cds_lfht_mm_order;
+extern const struct cds_lfht_mm_type cds_lfht_mm_chunk;
 
 /*
  * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.