From: Mathieu Desnoyers Date: Tue, 21 Aug 2012 13:08:46 +0000 (-0400) Subject: rcuja: add fallback nodes X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=f07b240f5d4b2c086abedcdd4f6516753fd934e4;p=urcu.git rcuja: add fallback nodes Signed-off-by: Mathieu Desnoyers --- diff --git a/rcuja/rcuja-internal.h b/rcuja/rcuja-internal.h index 67d121b..74ee728 100644 --- a/rcuja/rcuja-internal.h +++ b/rcuja/rcuja-internal.h @@ -46,6 +46,7 @@ struct cds_ja_shadow_node { unsigned int nr_child; /* number of children in node */ struct rcu_head head; /* for deferred node and shadow node reclaim */ int is_root; /* is it a root node ? */ + int fallback_removal_count; /* removals left keeping fallback */ }; struct cds_ja { @@ -58,6 +59,7 @@ struct cds_ja { * cache footprint, especially for very small nodes. */ struct cds_lfht *ht; + unsigned long nr_fallback; /* Number of fallback nodes used */ }; __attribute__((visibility("protected"))) @@ -68,7 +70,7 @@ __attribute__((visibility("protected"))) void rcuja_shadow_unlock(struct cds_ja_shadow_node *shadow_node); __attribute__((visibility("protected"))) -int rcuja_shadow_set(struct cds_lfht *ht, +struct cds_ja_shadow_node *rcuja_shadow_set(struct cds_lfht *ht, struct cds_ja_inode *new_node, struct cds_ja_shadow_node *inherit_from); diff --git a/rcuja/rcuja-shadow-nodes.c b/rcuja/rcuja-shadow-nodes.c index 3a5de33..89b4c45 100644 --- a/rcuja/rcuja-shadow-nodes.c +++ b/rcuja/rcuja-shadow-nodes.c @@ -220,7 +220,7 @@ void rcuja_shadow_unlock(struct cds_ja_shadow_node *shadow_node) } __attribute__((visibility("protected"))) -int rcuja_shadow_set(struct cds_lfht *ht, +struct cds_ja_shadow_node *rcuja_shadow_set(struct cds_lfht *ht, struct cds_ja_inode *new_node, struct cds_ja_shadow_node *inherit_from) { @@ -230,7 +230,7 @@ int rcuja_shadow_set(struct cds_lfht *ht, shadow_node = calloc(sizeof(*shadow_node), 1); if (!shadow_node) - return -ENOMEM; + return NULL; shadow_node->node = new_node; /* @@ -242,7 +242,7 @@ int rcuja_shadow_set(struct cds_lfht *ht, shadow_node->lock = calloc(sizeof(*shadow_node->lock), 1); if (!shadow_node->lock) { free(shadow_node); - return -ENOMEM; + return NULL; } pthread_mutex_init(shadow_node->lock, NULL); } @@ -258,9 +258,9 @@ int rcuja_shadow_set(struct cds_lfht *ht, if (ret_node != &shadow_node->ht_node) { free(shadow_node); - return -EEXIST; + return NULL; } - return 0; + return shadow_node; } static diff --git a/rcuja/rcuja.c b/rcuja/rcuja.c index 64c6c42..ff018e6 100644 --- a/rcuja/rcuja.c +++ b/rcuja/rcuja.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include "rcuja-internal.h" @@ -80,6 +81,12 @@ struct cds_ja_type { */ #define NODE_INDEX_NULL 8 +/* + * Number of removals needed on a fallback node before we try to shrink + * it. + */ +#define JA_FALLBACK_REMOVAL_COUNT 8 + /* * Iteration on the array to find the right node size for the number of * children stops when it reaches .max_child == 256 (this is the largest @@ -581,18 +588,20 @@ int ja_node_recompact_add(struct cds_ja *ja, { unsigned int new_type_index; struct cds_ja_inode *new_node; + struct cds_ja_shadow_node *new_shadow_node; const struct cds_ja_type *new_type; struct cds_ja_inode_flag *new_node_flag; - int new_shadow = 0; int ret; + int fallback = 0; if (!shadow_node || old_type_index == NODE_INDEX_NULL) { new_type_index = 0; } else { new_type_index = old_type_index + 1; } - dbg_printf("Recompact to type %d\n", new_type_index); +retry: /* for fallback */ + dbg_printf("Recompact to type %d\n", new_type_index); new_type = &ja_types[new_type_index]; new_node = alloc_cds_ja_node(new_type); if (!new_node) @@ -600,23 +609,14 @@ int ja_node_recompact_add(struct cds_ja *ja, new_node_flag = ja_node_flag(new_node, new_type_index); dbg_printf("Recompact inherit lock from %p\n", shadow_node); - ret = rcuja_shadow_set(ja->ht, new_node, shadow_node); - if (ret) { + new_shadow_node = rcuja_shadow_set(ja->ht, new_node, shadow_node); + if (!new_shadow_node) { free(new_node); - return ret; - } - - if (!shadow_node) { - shadow_node = rcuja_shadow_lookup_lock(ja->ht, new_node); - assert(shadow_node); - new_shadow = 1; + return -ENOMEM; } - - /* - * We need to clear nr_child, because it will be re-incremented - * by _ja_node_set_nth(). - */ - shadow_node->nr_child = 0; + if (fallback) + new_shadow_node->fallback_removal_count = + JA_FALLBACK_REMOVAL_COUNT; assert(old_type->type_class != RCU_JA_PIGEON); switch (old_type->type_class) { @@ -633,8 +633,12 @@ int ja_node_recompact_add(struct cds_ja *ja, ja_linear_node_get_ith_pos(old_type, old_node, i, &v, &iter); if (!iter) continue; - ret = _ja_node_set_nth(new_type, new_node, shadow_node, + ret = _ja_node_set_nth(new_type, new_node, + new_shadow_node, v, iter); + if (new_type->type_class == RCU_JA_POOL && ret) { + goto fallback_toosmall; + } assert(!ret); } break; @@ -659,8 +663,13 @@ int ja_node_recompact_add(struct cds_ja *ja, j, &v, &iter); if (!iter) continue; - ret = _ja_node_set_nth(new_type, new_node, shadow_node, + ret = _ja_node_set_nth(new_type, new_node, + new_shadow_node, v, iter); + if (new_type->type_class == RCU_JA_POOL + && ret) { + goto fallback_toosmall; + } assert(!ret); } } @@ -673,11 +682,12 @@ int ja_node_recompact_add(struct cds_ja *ja, default: assert(0); ret = -EINVAL; - goto unlock_new_shadow; + goto end; } /* add node */ - ret = _ja_node_set_nth(new_type, new_node, shadow_node, + ret = _ja_node_set_nth(new_type, new_node, + new_shadow_node, n, child_node_flag); assert(!ret); /* Return pointer to new recompacted new through old_node_flag */ @@ -689,11 +699,21 @@ int ja_node_recompact_add(struct cds_ja *ja, } ret = 0; - -unlock_new_shadow: - if (new_shadow) - rcuja_shadow_unlock(shadow_node); +end: return ret; + +fallback_toosmall: + /* fallback if next pool is too small */ + ret = rcuja_shadow_clear(ja->ht, new_node, new_shadow_node, + RCUJA_SHADOW_CLEAR_FREE_NODE); + assert(!ret); + + /* Last type: pigeon */ + new_type_index = (1UL << JA_TYPE_BITS) - 1; + dbg_printf("Fallback to type %d\n", new_type_index); + uatomic_inc(&ja->nr_fallback); + fallback = 1; + goto retry; } /* @@ -775,7 +795,8 @@ int ja_attach_node(struct cds_ja *ja, struct cds_ja_node *child_node) { struct cds_ja_shadow_node *shadow_node = NULL, - *parent_shadow_node = NULL; + *parent_shadow_node = NULL, + *iter_shadow_node; struct cds_ja_inode *node = ja_node_ptr(node_flag); struct cds_ja_inode *parent_node = ja_node_ptr(parent_node_flag); struct cds_hlist_head head; @@ -808,9 +829,12 @@ int ja_attach_node(struct cds_ja *ja, /* Create shadow node for the leaf node */ dbg_printf("leaf shadow node creation\n"); - ret = rcuja_shadow_set(ja->ht, ja_node_ptr(iter_node_flag), NULL); - if (ret) + iter_shadow_node = rcuja_shadow_set(ja->ht, + ja_node_ptr(iter_node_flag), NULL); + if (!iter_shadow_node) { + ret = -ENOMEM; goto check_error; + } created_nodes[nr_created_nodes++] = iter_node_flag; for (i = ja->tree_depth - 1; i >= (int) depth; i--) { @@ -962,6 +986,7 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits, { struct cds_ja *ja; int ret; + struct cds_ja_shadow_node *root_shadow_node; ja = calloc(sizeof(*ja), 1); if (!ja) @@ -995,11 +1020,13 @@ struct cds_ja *_cds_ja_new(unsigned int key_bits, /* * Note: we should not free this node until judy array destroy. */ - ret = rcuja_shadow_set(ja->ht, + root_shadow_node = rcuja_shadow_set(ja->ht, ja_node_ptr((struct cds_ja_inode_flag *) &ja->root), NULL); - if (ret) + if (!root_shadow_node) { + ret = -ENOMEM; goto ht_node_error; + } return ja; @@ -1026,6 +1053,10 @@ int cds_ja_destroy(struct cds_ja *ja) ret = rcuja_delete_ht(ja->ht); if (ret) return ret; + if (uatomic_read(&ja->nr_fallback)) + fprintf(stderr, + "[warning] RCU Judy Array used %lu fallback node(s)\n", + uatomic_read(&ja->nr_fallback)); free(ja); return 0; }