logging: include swap usage

This includes swap usage in the log output. It's useful for doing
analysis of memory config on performance, and can serve as useful input
when collecting other performance data since swapping almost always
impacts runtime perf.

src/logging.cpp

@@ -125,7 +125,8 @@ static void writeFileHeaders(ofstream& out){
     if (HUDElements.params->enabled[OVERLAY_PARAM_ENABLED_log_versioning])
       out << "--------------------FRAME METRICS--------------------" << endl;
 
-    out << "fps," << "frametime," << "cpu_load," << "gpu_load," << "cpu_temp," << "gpu_temp," << "gpu_core_clock," << "gpu_mem_clock," << "gpu_vram_used," << "gpu_power," << "ram_used," << "elapsed" << endl;
+    out << "fps," << "frametime," << "cpu_load," << "gpu_load," << "cpu_temp," << "gpu_temp," << "gpu_core_clock," << "gpu_mem_clock," << "gpu_vram_used," << "gpu_power," << "ram_used," << "swap_used," << "elapsed" << endl;
+
 }
 
 void Logger::writeToFile(){
@@ -147,6 +148,7 @@ void Logger::writeToFile(){
     output_file << logArray.back().gpu_vram_used << ",";
     output_file << logArray.back().gpu_power << ",";
     output_file << logArray.back().ram_used << ",";
+    output_file << logArray.back().swap_used << ",";
     output_file << std::chrono::duration_cast<std::chrono::nanoseconds>(logArray.back().previous).count() << "\n";
     output_file.flush();
   } else {

src/logging.h

@@ -25,6 +25,7 @@ struct logData{
   int gpu_power;
   float gpu_vram_used;
   float ram_used;
+  float swap_used;
 
   Clock::duration previous;
 };

src/overlay.cpp

@@ -158,6 +158,7 @@ void update_hw_info(const struct overlay_params& params, uint32_t vendorID)
    currentLogData.gpu_power = gpu_info.powerUsage;
 #ifdef __linux__
    currentLogData.ram_used = memused;
+   currentLogData.swap_used = swapused;
 #endif
 
    currentLogData.cpu_load = cpuStats.GetCPUDataTotal().percent;