[lttng-dev] [PATCH 11/12] add rculfhash-mm-chunk.c memory management

[Lai Jiangshan]

Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
---
 Makefile.am          |    2 +-
 rculfhash-internal.h |    9 ++++
 rculfhash-mm-chunk.c |  107 ++++++++++++++++++++++++++++++++++++++++++++++++++
 urcu/rculfhash.h     |    1 +
 4 files changed, 118 insertions(+), 1 deletions(-)
 create mode 100644 rculfhash-mm-chunk.c

diff --git a/Makefile.am b/Makefile.am
index 4d3f7bd..853ecd5 100644
--- 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 820e62c..fda4251 100644
--- 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 +96,13 @@ 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(avoid to alloc chunks with different
+		 * size). chunks improve cache locality for small index orders
+		 */
+		struct cds_lfht_node *tbl_chunk[0];
 	};
 };
 
diff --git a/rculfhash-mm-chunk.c b/rculfhash-mm-chunk.c
new file mode 100644
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 at 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 926aa14..54e0cd8 100644
--- 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.
-- 
1.7.4.4