clean up num_gpu calculation code (#673)

llm/llama.go

@@ -218,7 +218,6 @@ func NumGPU(numLayer, fileSizeBytes int64, opts api.Options) int {
 	if opts.NumGPU != -1 {
 		return opts.NumGPU
 	}
-	n := 1 // default to enable metal on macOS
 	if runtime.GOOS == "linux" {
 		vramMib, err := CheckVRAM()
 		if err != nil {
@@ -235,10 +234,11 @@ func NumGPU(numLayer, fileSizeBytes int64, opts api.Options) int {
 		// TODO: this is a rough heuristic, better would be to calculate this based on number of layers and context size
 		bytesPerLayer := fileSizeBytes / numLayer
 
-		// set n to the max number of layers we can fit in VRAM
-		return int(totalVramBytes / bytesPerLayer)
+		// max number of layers we can fit in VRAM
+		layers := int(totalVramBytes / bytesPerLayer)
+		log.Printf("%d MiB VRAM available, loading up to %d GPU layers", vramMib, layers)
 
-		log.Printf("%d MiB VRAM available, loading up to %d GPU layers", vramMib, n)
+		return layers
 	}
 	// default to enable metal on macOS
 	return 1