[ltt-dev] [PATCH 5/6 respin] directly lookup bucket in the first order table

[Mathieu Desnoyers]

Merged as:
 
commit ef6e6171a5046d56c3f4a32abcf3436546977118
Author: Lai Jiangshan <laijs at cn.fujitsu.com>
Date:   Fri Oct 28 08:14:07 2011 +0200

    rculfhash: directly lookup bucket in the first order table
    
    [ Edit by Mathieu Desnoyers: add a dbg_printf so the start-of-table
      lookup prints the same dbg messages as normal lookups. ]
    
    Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>

diff --git a/rculfhash.c b/rculfhash.c
index 675ef38..1f6ee71 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -738,17 +738,21 @@ struct _cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
 
 	assert(size > 0);
 	index = hash & (size - 1);
+
+	if (index < ht->min_alloc_size) {
+		dbg_printf("lookup hash %lu index %lu order 0 aridx 0\n",
+			   hash, index);
+		return &ht->t.tbl[0]->nodes[index];
+	}
 	/*
 	 * equivalent to get_count_order_ulong(index + 1), but optimizes
 	 * away the non-existing 0 special-case for
 	 * get_count_order_ulong.
 	 */
 	order = fls_ulong(index);
-
 	dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
-		   hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1)));
-
-	return &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+		   hash, index, order, index & ((1UL << (order - 1)) - 1));
+	return &ht->t.tbl[order]->nodes[index & ((1UL << (order - 1)) - 1)];
 }
 
 /*

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com