rcuja 1d distribution: cleanup

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c
index 34f3191a39037c24a058d33f0ebfabc405c0a82c..fb1dccb7f093e167034bd6042846c4c8f53ce2ec 100644 (file)
--- a/rcuja/rcuja.c
+++ b/rcuja/rcuja.c
@@ -793,7 +793,6 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
 
                for (i = 0; i < nr_child; i++) {
                        struct cds_ja_inode_flag *iter;
-                       unsigned int bit;
                        uint8_t v;
 
                        ja_linear_node_get_ith_pos(type, node, i, &v, &iter);
@@ -801,9 +800,9 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
                                continue;
                        if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
                                continue;
-                       for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
-                               if (v & (1U << bit))
-                                       nr_one[bit]++;
+                       for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
+                               if (v & (1U << bit_i))
+                                       nr_one[bit_i]++;
                        }
                        distrib_nr_child++;
                }
@@ -823,7 +822,6 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
 
                        for (j = 0; j < nr_child; j++) {
                                struct cds_ja_inode_flag *iter;
-                               unsigned int bit;
                                uint8_t v;
 
                                ja_linear_node_get_ith_pos(type, pool,
@@ -832,9 +830,9 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
                                        continue;
                                if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
                                        continue;
-                               for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
-                                       if (v & (1U << bit))
-                                               nr_one[bit]++;
+                               for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
+                                       if (v & (1U << bit_i))
+                                               nr_one[bit_i]++;
                                }
                                distrib_nr_child++;
                        }
@@ -850,16 +848,15 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
                nr_child = shadow_node->nr_child;
                for (i = 0; i < nr_child; i++) {
                        struct cds_ja_inode_flag *iter;
-                       unsigned int bit;
 
                        iter = ja_pigeon_node_get_ith_pos(type, node, i);
                        if (!iter)
                                continue;
                        if (mode == JA_RECOMPACT_DEL && *nullify_node_flag_ptr == iter)
                                continue;
-                       for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
-                               if (i & (1U << bit))
-                                       nr_one[bit]++;
+                       for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
+                               if (i & (1U << bit_i))
+                                       nr_one[bit_i]++;
                        }
                        distrib_nr_child++;
                }
@@ -874,11 +871,9 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
        }
 
        if (mode == JA_RECOMPACT_ADD) {
-               unsigned int bit;
-
-               for (bit = 0; bit < JA_BITS_PER_BYTE; bit++) {
-                       if (n & (1U << bit))
-                               nr_one[bit]++;
+               for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
+                       if (n & (1U << bit_i))
+                               nr_one[bit_i]++;
                }
                distrib_nr_child++;
        }
@@ -886,12 +881,13 @@ unsigned int ja_node_sum_distribution_1d(enum ja_recompact mode,
        /*
         * The best bit selector is that for which the number of ones is
         * closest to half of the number of children in the
-        * distribution.
+        * distribution. We calculate the distance using the double of
+        * the sub-distribution sizes to eliminate truncation error.
         */
        for (bit_i = 0; bit_i < JA_BITS_PER_BYTE; bit_i++) {
                unsigned int distance_to_best;
 
-               distance_to_best = abs_int(nr_one[bit_i] - (distrib_nr_child >> 1U));
+               distance_to_best = abs_int((nr_one[bit_i] << 1U) - distrib_nr_child);
                if (distance_to_best < overall_best_distance) {
                        overall_best_distance = distance_to_best;
                        bitsel = bit_i;