def vhost_controller_set_coalescing(client, ctrlr, delay_base_us, iops_threshold):
    """Set coalescing for vhost controller.
    Args:
        ctrlr: controller name
        delay_base_us: base delay time
        iops_threshold: IOPS threshold when coalescing is enabled
    """
    params = {
        'ctrlr': ctrlr,
        'delay_base_us': delay_base_us,
        'iops_threshold': iops_threshold,
    }
    return client.call('vhost_controller_set_coalescing', params)