hv_get_avail_to_write_percent
u32 ring_avail = hv_get_avail_to_write_percent(&out_channel->outbound);
(hv_get_avail_to_write_percent(&channel->outbound) >
if (hv_get_avail_to_write_percent(&outgoing_channel->outbound)
if (hv_get_avail_to_write_percent(&channel->outbound)
if (hv_get_avail_to_write_percent(&channel->outbound)