Metrics available via XENSERVER if you want to build your own monitoring product for vGpu

Virtual GPU Forums More vGPU Forums Monitoring/Assessment Tools
1

There are 5 APIs that can expose these metrics c, c#, Python, Java and powershell http://blogs.citrix.com/2014/01/22/xenserverxendesktop-vgpu-new-metrics-available-to-monitor-nvidia-grid-gpus/