On 2017年01月07日 03:47, Michael S. Tsirkin wrote:
+static int tun_get_coalesce(struct net_device *dev, + struct ethtool_coalesce *ec) +{ + struct tun_struct *tun = netdev_priv(dev); + + ec->rx_max_coalesced_frames = tun->rx_batched; + + return 0; +} + +static int tun_set_coalesce(struct net_device *dev, + struct ethtool_coalesce *ec) +{ + struct tun_struct *tun = netdev_priv(dev); + + if (ec->rx_max_coalesced_frames > NAPI_POLL_WEIGHT) + return -EINVAL;So what should userspace do? Keep trying until it succeeds? I think it's better to just use NAPI_POLL_WEIGHT instead and DTRT here.
Well, looking at how set_coalesce is implemented in other drivers, -EINVAL is usually used when user give a value that exceeds the limitation. For tuntap, what missed here is probably just a documentation for coalescing in tuntap.txt. (Or extend ethtool to return the max value). This seems much better than silently reduce the value to the limitation.
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