add experimental nvml gpu collector (#1522)

agent/gpu_nvml_linux.go

@@ -0,0 +1,57 @@
+//go:build linux
+
+package agent
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/ebitengine/purego"
+	"golang.org/x/exp/slog"
+)
+
+func openLibrary(name string) (uintptr, error) {
+	return purego.Dlopen(name, purego.RTLD_NOW|purego.RTLD_GLOBAL)
+}
+
+func getNVMLPath() string {
+	return "libnvidia-ml.so.1"
+}
+
+func hasSymbol(lib uintptr, symbol string) bool {
+	_, err := purego.Dlsym(lib, symbol)
+	return err == nil
+}
+
+func (c *nvmlCollector) isGPUActive(bdf string) bool {
+	// runtime_status
+	statusPath := filepath.Join("/sys/bus/pci/devices", bdf, "power/runtime_status")
+	status, err := os.ReadFile(statusPath)
+	if err != nil {
+		slog.Debug("NVML: Can't read runtime_status", "bdf", bdf, "err", err)
+		return true // Assume active if we can't read status
+	}
+	statusStr := strings.TrimSpace(string(status))
+	if statusStr != "active" && statusStr != "resuming" {
+		slog.Debug("NVML: GPU not active", "bdf", bdf, "status", statusStr)
+		return false
+	}
+
+	// power_state (D0 check)
+	// Find any drm card device power_state
+	pstatePathPattern := filepath.Join("/sys/bus/pci/devices", bdf, "drm/card*/device/power_state")
+	matches, _ := filepath.Glob(pstatePathPattern)
+	if len(matches) > 0 {
+		pstate, err := os.ReadFile(matches[0])
+		if err == nil {
+			pstateStr := strings.TrimSpace(string(pstate))
+			if pstateStr != "D0" {
+				slog.Debug("NVML: GPU not in D0 state", "bdf", bdf, "pstate", pstateStr)
+				return false
+			}
+		}
+	}
+
+	return true
+}