Re: [PATCH net-next 12/20] net: hns3: Add packet statistics of netdev

[Jakub Kicinski]

On Mon, 08 Jan 2018 20:39:13 -0500 (EST), David Miller wrote:
> From: Jakub Kicinski <kubakici@xxxxx>
> Date: Mon, 8 Jan 2018 12:04:31 -0800
> 
> > Ugh, I so didn't review this in time :(  I think there is a consensus
> > that we should avoid duplicating standard stats in ethtool.  Especially
> > those old ones.  Like "collisions", I assume this is a modern NIC, are
> > collisions still a thing?  
> 
> There is no standard way to get per-queue values, and ethtool stats are
> how pretty much every driver provides it.

Right, agreed.  I'm only objecting to this patch (12/20), where we can
see the telltale code like this:

+	const struct rtnl_link_stats64 *net_stats;
+	struct rtnl_link_stats64 temp;
+
+	net_stats = dev_get_stats(netdev, &temp);
+	for (i = 0; i < HNS3_NETDEV_STATS_COUNT; i++) {
+		stat = (u8 *)net_stats + hns3_netdev_stats[i].stats_offset;
+		*data++ = *(u64 *)stat;
+	}

Where:

+#define HNS3_NETDEV_STAT(_string, _member)	{			\
+	.stats_string = _string,					\
+	.stats_offset = offsetof(struct rtnl_link_stats64, _member)	\
+}
+
+static const struct hns3_stats hns3_netdev_stats[] = {
+	/* Rx per-queue statistics */
+	HNS3_NETDEV_STAT("rx_packets", rx_packets),
+	HNS3_NETDEV_STAT("tx_packets", tx_packets),

etc.  IOW dumping struct rtnl_link_stats64 to ethtool -S member by
member.

Let me put the netlink per-queue stats on my soft TODO list :)