rdma rumtime extend block restriction

Author: yanglimingcn

src/brpc/rdma/block_pool.cpp

@@ -36,7 +36,7 @@ DEFINE_int32(rdma_memory_pool_initial_size_mb, 1024,
              "Initial size of memory pool for RDMA (MB)");
 DEFINE_int32(rdma_memory_pool_increase_size_mb, 1024,
              "Increased size of memory pool for RDMA (MB)");
-DEFINE_int32(rdma_memory_pool_max_regions, 1, "Max number of regions");
+DEFINE_int32(rdma_memory_pool_max_regions, 3, "Max number of regions");
 DEFINE_int32(rdma_memory_pool_buckets, 4, "Number of buckets to reduce race");
 DEFINE_int32(rdma_memory_pool_tls_cache_num, 128, "Number of cached block in tls");
 DEFINE_bool(rdma_memory_pool_user_specified_memory, false,
@@ -96,6 +96,7 @@ struct GlobalInfo {
     std::vector<IdleNode*> idle_list[BLOCK_SIZE_COUNT];
     std::vector<butil::Mutex*> lock[BLOCK_SIZE_COUNT];
     std::vector<size_t> idle_size[BLOCK_SIZE_COUNT];
+    int region_num[BLOCK_SIZE_COUNT];
     butil::Mutex extend_lock;
 };
 static GlobalInfo* g_info = NULL;
@@ -128,10 +129,30 @@ uint32_t GetRegionId(const void* buf) {
     return r->id;
 }
 
+// When both rdma_memory_pool_max_regions and rdma_memory_pool_buckets are
+// greater than 1, dynamic memory expansion may cause concurrent modification
+// issues in the memory linked list due to lock contention problems. To address
+// this, we increase the region_num count for each block_type. Dynamic memory
+// expansion is only permitted when both of the following conditions are met:
+// rdma_memory_pool_buckets equals 1
+// g_info->region_num[block_type] is less than 1
+static bool CanExtendBlockRuntime(int block_type) {
+    return FLAGS_rdma_memory_pool_buckets == 1 ||
+           g_info->region_num[block_type] < 1;
+}
+
 static void* ExtendBlockPoolImpl(void* region_base, size_t region_size,
                                  int block_type) {
+    if (CanExtendBlockRuntime(block_type) == false) {
+        LOG(INFO) << "Runtime extend memory only support one bucket or region "
+                     "num is zero for per block_type";
+        free(region_base);
+        errno = ENOMEM;
+        return NULL;
+    }
     if (g_region_num == FLAGS_rdma_memory_pool_max_regions) {
         LOG(INFO) << "Memory pool reaches max regions";
+        free(region_base);
         errno = ENOMEM;
         return NULL;
     }
@@ -167,6 +188,7 @@ static void* ExtendBlockPoolImpl(void* region_base, size_t region_size,
         g_info->idle_list[block_type][i] = node[i];
         g_info->idle_size[block_type][i] += node[i]->len;
     }
+    g_info->region_num[block_type]++;
 
     return region_base;
 }
@@ -214,12 +236,6 @@ void* ExtendBlockPoolByUser(void* region_base, size_t region_size,
     uint64_t index = butil::fast_rand() % g_buckets;
     BAIDU_SCOPED_LOCK(*g_info->lock[block_type][index]);
     BAIDU_SCOPED_LOCK(g_info->extend_lock);
-
-    if (g_region_num > 1 && FLAGS_rdma_memory_pool_buckets > 1) {
-        LOG_EVERY_SECOND(ERROR)
-            << "Runtime extend memory only support single bucket";
-        return NULL;
-    }
     region_size =
         region_size * BYTES_IN_MB / g_block_size[block_type] / g_buckets;
     region_size *= g_block_size[block_type] * g_buckets;
@@ -274,14 +290,7 @@ bool InitBlockPool(RegisterCallback cb) {
         errno = EINVAL;
         return false;
     }
-    // runtime extend block pool only support 1 bucket
-    if (FLAGS_rdma_memory_pool_max_regions > 1 &&
-        FLAGS_rdma_memory_pool_buckets > 1) {
-        LOG(WARNING) << "rdma runtime extend block pool only support 1 bucket";
-        return false;
-    }
     g_buckets = FLAGS_rdma_memory_pool_buckets;
-
     g_info = new (std::nothrow) GlobalInfo;
     if (!g_info) {
         return false;
@@ -300,6 +309,7 @@ bool InitBlockPool(RegisterCallback cb) {
         if (g_info->idle_size[i].size() != g_buckets) {
             return false;
         }
+        g_info->region_num[i] = 0;
         for (size_t j = 0; j < g_buckets; ++j) {
             g_info->lock[i][j] = new (std::nothrow) butil::Mutex;
             if (!g_info->lock[i][j]) {