usegpu_f()
{
if [ -z "$1" ]; then
  if [ -z "$CUDA_VISIBLE_DEVICES" ]; then
    echo ALL GPU will be used.
  else
    echo current GPU: $CUDA_VISIBLE_DEVICES.
  fi
  return
else
  export CUDA_VISIBLE_DEVICES="$1"
fi
}
export CUDA_DEVICE_ORDER=PCI_BUS_ID
alias usegpu='usegpu_f'