Difference between (struct tc_stats) and (struct net_device_stats)

[N N Ashok <nalkunda@xxxxxxxxxxx>]

Hi All,
   The tc_stats and net_device_stats are defined as below:
struct tc_stats
{
        __u64   bytes;                  /* NUmber of enqueues bytes */
        __u32   packets;                /* Number of enqueued packets   */
        __u32   drops;                  /* Packets dropped because of lack of 
resources */
        __u32   overlimits;             /* Number of throttle events when this
<snip>
};
struct net_device_stats
{
        unsigned long   rx_packets;             /* total packets received       
*/
        unsigned long   tx_packets;             /* total packets transmitted    
*/
        unsigned long   rx_bytes;               /* total bytes received         
*/
        unsigned long   tx_bytes;               /* total bytes transmitted      
*/
        unsigned long   rx_errors;              /* bad packets received         
*/
        unsigned long   tx_errors;              /* packet transmit problems     
*/
        unsigned long   rx_dropped;             /* no space in linux buffers    
*/
        unsigned long   tx_dropped;             /* no space available in linux  
*/
        unsigned long   multicast;              /* multicast packets received   
*/
        unsigned long   collisions;
<snip>
};

      I add an estimator to one of my interfaces and if I observe, the 
bytes,packets in tc_stats for the estimator are not the same as rx_packets, 
rx_bytes of net_device_stats obtainted by get_stats(dev) of the same 
interface at almost the same time. Is there a difference in the meaning/range 
of the two structure fields? In net_device_stats, we have counts for drops, 
errors but no such fields for tc_stats. Are these counts also included in the 
bytes, packets fields of tc_stats?

Thanks,
Ashok