MS-312 Set openmp thread number by config

Former-commit-id: 6ef7343aa6b908e6cd319271d4c60a49789eaf03

cpp/CHANGELOG.md

@@ -40,6 +40,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-266 - Improve topk reduce time by using multi-threads
 - MS-275 - Avoid sqlite logic error excetion
 - MS-278 - add IndexStatsHelper
+- MS-312 - Set openmp thread number by config
 
 ## New Feature
 - MS-180 - Add new mem manager

cpp/conf/server_config.template

@@ -43,4 +43,5 @@ engine_config:
   nprobe: 10
   nlist: 16384
   use_blas_threshold: 20
-  metric_type: L2       # compare vectors by euclidean distance(L2) or inner product(IP), optional: L2 or IP
+  metric_type: L2               # compare vectors by euclidean distance(L2) or inner product(IP), optional: L2 or IP
+  omp_thread_occupancy: 0.75    # how many compute threads be used, this is a percent value compare to system cpu core number(for instance: cpu core is 4, then 0.75 means use 3 compute threads)

cpp/src/server/DBWrapper.cpp

@@ -10,11 +10,14 @@
 #include "utils/Log.h"
 #include "utils/StringHelpFunctions.h"
 
+#include <omp.h>
+
 namespace zilliz {
 namespace milvus {
 namespace server {
 
 DBWrapper::DBWrapper() {
+    //db config
     zilliz::milvus::engine::Options opt;
     ConfigNode& db_config = ServerConfig::GetInstance().GetConfig(CONFIG_DB);
     opt.meta.backend_uri = db_config.GetValue(CONFIG_DB_URL);
@@ -37,6 +40,7 @@ DBWrapper::DBWrapper() {
         kill(0, SIGUSR1);
     }
 
+    // cache config
     ConfigNode& cache_config = ServerConfig::GetInstance().GetConfig(CONFIG_CACHE);
     opt.insert_cache_immediately_ = cache_config.GetBoolValue(CONFIG_INSERT_CACHE_IMMEDIATELY, false);
 
@@ -56,6 +60,16 @@ DBWrapper::DBWrapper() {
         kill(0, SIGUSR1);
     }
 
+    // engine config
+    ConfigNode& engine_config = ServerConfig::GetInstance().GetConfig(CONFIG_ENGINE);
+    float omp_thread_rate = engine_config.GetFloatValue(CONFIG_OMP_THREAD_RATE, 0.75);
+    uint32_t cpu_count = 1;
+    CommonUtil::GetSystemAvailableThreads(cpu_count);
+    float thread_count = omp_thread_rate*(float)cpu_count;
+    int32_t omp_thread = (int32_t)round(thread_count);
+    omp_set_num_threads(omp_thread);
+    SERVER_LOG_DEBUG << "Openmp thread number = " << omp_thread;
+
     //set archive config
     engine::ArchiveConf::CriteriaT criterial;
     int64_t disk = db_config.GetInt64Value(CONFIG_DB_ARCHIVE_DISK, 0);

cpp/src/server/ServerConfig.h

@@ -53,6 +53,7 @@ static const std::string CONFIG_NPROBE = "nprobe";
 static const std::string CONFIG_NLIST = "nlist";
 static const std::string CONFIG_DCBT = "use_blas_threshold";
 static const std::string CONFIG_METRICTYPE = "metric_type";
+static const std::string CONFIG_OMP_THREAD_RATE = "omp_thread_occupancy";
 
 class ServerConfig {
  public: