benchmark/nixlbench: --config_file param supported

This patch introduces config file support to nixlbench.

The name of a config file can be specified using the --config_file
command-line parameter. The config file is in INI format.

Each existing command-line parameter can also be placed in the
"[global]" section of the configuration file, so the following
invocations:

  nixlbench --etcd_endpoints http://localhost:2379 --backend POSIX
    --filepath /mnt/test --posix_api_type AIO

and

  nixlbench --config_file /tmp/nixlbench.config

where /tmp/nixlbench.config contains:

[global]
etcd_endpoints=http://localhost:2379
backend=POSIX
filepath=/mnt/test
posix_api_type=AIO

are identical.

If a parameter exists in the config file and is also explicitly
specified on the command line, the latter takes precedence.

Signed-off-by: Anton Nayshtut <anayshtut@nvidia.com>

Author: anton-nayshtut

benchmark/nixlbench/src/utils/utils.cpp

@@ -71,6 +71,7 @@ struct xferBenchParamInfo
  * xferBench Config
  **********/
 const xferBenchParamInfo xbench_params[] = {
+NB_ARG_STRING(config_file, "", "Config file (Default: None)")
 NB_ARG_STRING(benchmark_group, "default", \
               "Name of benchmark group. Use different names to run multiple benchmarks in parallel " \
               "(Default: default)")
@@ -165,6 +166,7 @@ NB_ARG_STRING(gusli_device_security, "", \
 #undef NB_ARG_BOOL
 #undef NB_ARG_STRING
 
+std::string xferBenchConfig::config_file = "";
 std::string xferBenchConfig::runtime_type = "";
 std::string xferBenchConfig::worker_type = "";
 std::string xferBenchConfig::backend = "";
@@ -262,10 +264,42 @@ xferBenchConfig::parseConfig(int argc, char *argv[])
     return loadParams(result);
 }
 
+// getParamValue() provides a parameter value, giving priority to explicitly passed
+// parameters over those specified in the config_file or set as defaults.
+template <class T>
+T
+xferBenchConfig::getParamValue(std::unique_ptr<inih::INIReader> &ini, cxxopts::ParseResult &result, const char *name)
+{
+    if (ini && !result.count(name)) {
+        // config_file exists and the parameter is not specified explicitly ->
+        // try to read the value from config_file first
+        try {
+            return ini->Get<T>("global", name);
+        } catch (std::runtime_error&) {
+            // the parameter is not in the config_file -> fallback to ParseResult
+        }
+    }
+
+    return result[name].as<T>();
+}
+
 int
 xferBenchConfig::loadParams(cxxopts::ParseResult &result) {
+    std::unique_ptr<inih::INIReader> ini;
+
+    if (result.count("config_file")) {
+        /* if config_file parameter specified - try to read the config from file */
+        config_file = result["config_file"].as<std::string>();
+        try {
+            ini = std::make_unique<inih::INIReader>(config_file);
+        } catch (std::runtime_error& e) {
+            std::cerr << "Failed to load ini: " << e.what() << std::endl;
+            return -1;
+        }
+    }
+
 #define NB_ARG(name) \
-    result[#name].as<decltype(name)>()
+    getParamValue<decltype(name)>(ini, result, #name)
 
     benchmark_group = NB_ARG(benchmark_group);
     runtime_type = NB_ARG(runtime_type);

benchmark/nixlbench/src/utils/utils.h

@@ -29,6 +29,7 @@
 #include <utils/common/nixl_time.h>
 #include "runtime/runtime.h"
 #include "utils/cxxopts.hpp"
+#include "utils/ini.h"
 
 #if HAVE_CUDA
 #include <cuda.h>
@@ -125,6 +126,7 @@
                               XFERBENCH_MODE_MG == xferBenchConfig::mode)
 class xferBenchConfig {
     public:
+        static std::string config_file;
         static std::string runtime_type;
         static std::string worker_type;
         static std::string backend;
@@ -193,7 +195,10 @@ class xferBenchConfig {
 
 protected:
         static int
-        loadParams(cxxopts::ParseResult &options);
+        loadParams(cxxopts::ParseResult &result);
+        template <class T>
+        static T
+        getParamValue(std::unique_ptr<inih::INIReader> &ini, cxxopts::ParseResult &result, const char *name);
 };
 
 // Shared GUSLI device config used by utils and nixl_worker