[Cake] [PATCH 1/3] pkt_sched.h: add support for sch_cake API

[Stephen Hemminger]

On Tue, 21 Nov 2017 16:09:40 -0800
Dave Taht <dave.taht at gmail.com> wrote:

>  
> +/* CAKE */
> +enum {
> +	TCA_CAKE_UNSPEC,
> +	TCA_CAKE_BASE_RATE,
> +	TCA_CAKE_DIFFSERV_MODE,
> +	TCA_CAKE_ATM,
> +	TCA_CAKE_FLOW_MODE,
> +	TCA_CAKE_OVERHEAD,
> +	TCA_CAKE_RTT,
> +	TCA_CAKE_TARGET,
> +	TCA_CAKE_AUTORATE,
> +	TCA_CAKE_MEMORY,
> +	TCA_CAKE_NAT,
> +	TCA_CAKE_ETHERNET,
> +	TCA_CAKE_WASH,
> +	TCA_CAKE_MPU,
> +	TCA_CAKE_INGRESS,
> +	TCA_CAKE_ACK_FILTER,
> +	__TCA_CAKE_MAX
> +};
> +#define TCA_CAKE_MAX	(__TCA_CAKE_MAX - 1)
> +
> +struct tc_cake_traffic_stats {
> +	__u32 packets;
> +	__u32 link_ms;
> +	__u64 bytes;
> +};
> +
> +#define TC_CAKE_MAX_TINS (8)
> +struct tc_cake_xstats {
> +	__u16 version;  /* == 5, increments when struct extended */
> +	__u8  max_tins; /* == TC_CAKE_MAX_TINS */
> +	__u8  tin_cnt;  /* <= TC_CAKE_MAX_TINS */
> +
> +	__u32 threshold_rate[TC_CAKE_MAX_TINS];
> +	__u32 target_us[TC_CAKE_MAX_TINS];
> +	struct tc_cake_traffic_stats sent[TC_CAKE_MAX_TINS];
> +	struct tc_cake_traffic_stats dropped[TC_CAKE_MAX_TINS];
> +	struct tc_cake_traffic_stats ecn_marked[TC_CAKE_MAX_TINS];
> +	struct tc_cake_traffic_stats backlog[TC_CAKE_MAX_TINS];
> +	__u32 interval_us[TC_CAKE_MAX_TINS];
> +	__u32 way_indirect_hits[TC_CAKE_MAX_TINS];
> +	__u32 way_misses[TC_CAKE_MAX_TINS];
> +	__u32 way_collisions[TC_CAKE_MAX_TINS];
> +	__u32 peak_delay_us[TC_CAKE_MAX_TINS]; /* ~= bulk flow delay */
> +	__u32 avge_delay_us[TC_CAKE_MAX_TINS];
> +	__u32 base_delay_us[TC_CAKE_MAX_TINS]; /* ~= sparse flows delay */
> +	__u16 sparse_flows[TC_CAKE_MAX_TINS];
> +	__u16 bulk_flows[TC_CAKE_MAX_TINS];
> +	__u16 unresponse_flows[TC_CAKE_MAX_TINS]; /* v4 - was u32 last_len */
> +	__u16 spare[TC_CAKE_MAX_TINS]; /* v4 - split last_len */
> +	__u32 max_skblen[TC_CAKE_MAX_TINS];
> +	__u32 capacity_estimate;  /* version 2 */
> +	__u32 memory_limit;       /* version 3 */
> +	__u32 memory_used;	  /* version 3 */
> +	struct tc_cake_traffic_stats ack_drops[TC_CAKE_MAX_TINS]; /* v5 */
> +};
> +

Rather than passing one big structure (like xstats) through netlink, it is more typical
to break it into separate TLV items.

Also, when I see multiple arrays of same size. It seems the API should
be:
	struct tc_cake_tin_stats {
		__u32 threshold_rate;
		__u32 target_us;
		struct tc_cake_traffic_stats sent;
...

What if you want to change number of TINS, the ABI shouldn't have to change.