Add unified memory support for NVIDIA GPUs

Detect and handle NVIDIA GPUs with unified memory architecture (e.g., GB10)
that use system RAM instead of dedicated VRAM. When nvmlDeviceGetMemoryInfo
fails or returns zero memory, fall back to querying system memory via sysinfo()
to report total, used, and free memory statistics.

This approach mirrors the existing unified memory handling for Apple M1/M2 GPUs
and enables proper memory monitoring for NVIDIA GPUs with integrated graphics.

Author: sbhavani

src/extract_gpuinfo_nvidia.c

@@ -29,6 +29,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/sysinfo.h>
 
 #define NVML_SUCCESS 0
 #define NVML_ERROR_INSUFFICIENT_SIZE 7
@@ -607,26 +608,62 @@ static void gpuinfo_nvidia_refresh_dynamic_info(struct gpu_info *_gpu_info) {
 
   // Device memory info (total,used,free)
   bool got_meminfo = false;
+  bool has_unified_memory = false;
+
   if (nvmlDeviceGetMemoryInfo_v2) {
     nvmlMemory_v2_t memory_info;
     memory_info.version = 2;
     last_nvml_return_status = nvmlDeviceGetMemoryInfo_v2(device, &memory_info);
     if (last_nvml_return_status == NVML_SUCCESS) {
-      got_meminfo = true;
-      SET_GPUINFO_DYNAMIC(dynamic_info, total_memory, memory_info.total);
-      SET_GPUINFO_DYNAMIC(dynamic_info, used_memory, memory_info.used);
-      SET_GPUINFO_DYNAMIC(dynamic_info, free_memory, memory_info.free);
-      SET_GPUINFO_DYNAMIC(dynamic_info, mem_util_rate, memory_info.used * 100 / memory_info.total);
+      // Check if this is a unified memory GPU (total == 0 indicates unified memory)
+      if (memory_info.total == 0) {
+        has_unified_memory = true;
+      } else {
+        got_meminfo = true;
+        SET_GPUINFO_DYNAMIC(dynamic_info, total_memory, memory_info.total);
+        SET_GPUINFO_DYNAMIC(dynamic_info, used_memory, memory_info.used);
+        SET_GPUINFO_DYNAMIC(dynamic_info, free_memory, memory_info.free);
+        SET_GPUINFO_DYNAMIC(dynamic_info, mem_util_rate, memory_info.used * 100 / memory_info.total);
+      }
+    } else {
+      // Memory query failed - likely unified memory GPU (error code 13 = NOT_SUPPORTED)
+      has_unified_memory = true;
     }
   }
-  if (!got_meminfo && nvmlDeviceGetMemoryInfo) {
+  if (!got_meminfo && !has_unified_memory && nvmlDeviceGetMemoryInfo) {
     nvmlMemory_v1_t memory_info;
     last_nvml_return_status = nvmlDeviceGetMemoryInfo(device, &memory_info);
     if (last_nvml_return_status == NVML_SUCCESS) {
-      SET_GPUINFO_DYNAMIC(dynamic_info, total_memory, memory_info.total);
-      SET_GPUINFO_DYNAMIC(dynamic_info, used_memory, memory_info.used);
-      SET_GPUINFO_DYNAMIC(dynamic_info, free_memory, memory_info.free);
-      SET_GPUINFO_DYNAMIC(dynamic_info, mem_util_rate, memory_info.used * 100 / memory_info.total);
+      // Check if this is a unified memory GPU (total == 0 indicates unified memory)
+      if (memory_info.total == 0) {
+        has_unified_memory = true;
+      } else {
+        SET_GPUINFO_DYNAMIC(dynamic_info, total_memory, memory_info.total);
+        SET_GPUINFO_DYNAMIC(dynamic_info, used_memory, memory_info.used);
+        SET_GPUINFO_DYNAMIC(dynamic_info, free_memory, memory_info.free);
+        SET_GPUINFO_DYNAMIC(dynamic_info, mem_util_rate, memory_info.used * 100 / memory_info.total);
+      }
+    } else {
+      // Memory query failed - likely unified memory GPU
+      has_unified_memory = true;
+    }
+  }
+
+  // Handle unified memory GPUs - query system memory instead
+  if (has_unified_memory) {
+    struct sysinfo si;
+    if (sysinfo(&si) == 0) {
+      // Total system RAM
+      unsigned long long total_ram = si.totalram * si.mem_unit;
+      unsigned long long free_ram = si.freeram * si.mem_unit;
+      unsigned long long used_ram = total_ram - free_ram;
+
+      SET_GPUINFO_DYNAMIC(dynamic_info, total_memory, total_ram);
+      SET_GPUINFO_DYNAMIC(dynamic_info, used_memory, used_ram);
+      SET_GPUINFO_DYNAMIC(dynamic_info, free_memory, free_ram);
+      if (total_ram > 0) {
+        SET_GPUINFO_DYNAMIC(dynamic_info, mem_util_rate, used_ram * 100 / total_ram);
+      }
     }
   }