gnb: check for possible performance tunnig requirements

This includes CPU scaling governor and DRM KMS polling.
We print a warning if they scaling governor is not performance
and if KMS polling is enabled.

Author: alvasMan

apps/gnb/gnb.cpp

@@ -55,6 +55,7 @@
 #include "srsran/phy/lower/lower_phy_factory.h"
 #include "srsran/phy/upper/upper_phy_timing_notifier.h"
 #include "srsran/radio/radio_factory.h"
+#include "srsran/support/sysinfo.h"
 #include <atomic>
 #include <csignal>
 #include <unordered_map>
@@ -467,6 +468,11 @@ int main(int argc, char** argv)
                  get_cpu_feature_info());
   }
 
+  // Check some common causes of performance issues and
+  // print a warning if required.
+  check_cpu_governor(gnb_logger);
+  check_drm_kms_polling(gnb_logger);
+
   // Set layer-specific pcap options.
   std::unique_ptr<ngap_pcap> ngap_p = std::make_unique<ngap_pcap_impl>();
   if (gnb_cfg.pcap_cfg.ngap.enabled) {

include/srsran/support/sysinfo.h

@@ -0,0 +1,77 @@
+/*
+ *
+ * Copyright 2021-2023 Software Radio Systems Limited
+ *
+ * By using this file, you agree to the terms and conditions set
+ * forth in the LICENSE file which can be found at the top level of
+ * the distribution.
+ *
+ */
+
+#include "srsran/srslog/srslog.h"
+#include <fstream>
+#include <string>
+#include <thread>
+
+#pragma once
+
+/// \brief Check whether the CPU scaling governor is set to performance.
+///
+/// \param[in] logger to print warnings.
+/// \return True if we were able to read the sysfs scaling governor information.
+inline bool check_cpu_governor(srslog::basic_logger& logger)
+{
+  unsigned int n_cpus        = std::thread::hardware_concurrency();
+  std::string  filename_base = "/sys/devices/system/cpu/cpu";
+  for (unsigned int i = 0; i < n_cpus; ++i) {
+    std::string   filename = filename_base + std::to_string(i) + "/cpufreq/scaling_governor";
+    std::ifstream input(filename);
+    if (input.fail()) {
+      logger.warning("Could not check scaling governor. filename={} error=\"{}\"", filename, strerror(errno));
+      return false;
+    }
+    std::string gov;
+    std::getline(input, gov);
+    if (input.fail()) {
+      logger.warning("Could not check scaling governor. filename={} error=\"{}\"", filename, strerror(errno));
+      return false;
+    }
+    if (gov == "performance") {
+      logger.debug("CPU{} scaling governor is set to performance", i);
+    } else {
+      logger.warning(
+          "CPU{} scaling governor is not set to performance, which may hinder performance. You can set it to "
+          "performance using the "
+          "\"srsran_performance\" script",
+          i);
+    }
+  }
+  return true;
+}
+
+/// \brief Check whether the DRM KMS polling is set.
+///
+/// \param[in] logger to print warnings.
+/// \return True if we were able to read the sysfs for the DRM KMS polling information.
+inline bool check_drm_kms_polling(srslog::basic_logger& logger)
+{
+  std::string   filename = "/sys/module/drm_kms_helper/parameters/poll";
+  std::ifstream input(filename);
+  if (input.fail()) {
+    logger.warning("Could not check DRM KMS polling. filename={} error=\"{}\"", filename, strerror(errno));
+    return false;
+  }
+  std::string polling;
+  std::getline(input, polling);
+  if (input.fail()) {
+    logger.warning("Could not check DRM KMS polling. filename={} error=\"{}\"", filename, strerror(errno));
+    return false;
+  }
+  if (polling == "N") {
+    logger.debug("DRM KMS polling is disabled");
+  } else {
+    logger.warning("DRM KMS polling is enabled, which may hinder performance. You can disable it using the "
+                   "\"srsran_performance\" script");
+  }
+  return true;
+}