On AM3517 when receiving information from the CAN interface to generate a lot of Linux software interrupts

Mem: 32336K used, 204116K free, 0K shrd, 1568K buff, 6260K cached
CPU: 0% usr 21% sys 0% nic 35% idle 0% io 0% irq 42% sirq
Load average: 0.03 0.04 0.05 1/58 1009
  PID    PPID        USER     STAT     VSZ     %MEM     %CPU     COMMAND
1008     951        root         R      1472         1%        44%     ./a.out
  622         2        root       SW           0          0%          6%    [kworker/0:2]
  644         2        root       SW           0          0%          1%    [ksdioirqd/mmc1]
1009     951        root         R      2844          1%          1%    top
    45         2        root       SW           0          0%          0%    [irq/74-serial i]
   951    949        root         S      2844          1%          0%    -sh
   924        1        root         S      2732          1%          0%    /sbin/syslogd -n -C64 -m 20
   926        1        root         S      2668          1%          0%    /sbin/klogd -n
   917        1        root         S      2668          1%          0%    /usr/sbin/telnetd
   912        1   messageb    S       2436          1%          0%    /usr/bin/dbus-daemon --system
   949        1        root         S      2400          1%          0%    login -- root
   692        1        root         S <   2188          1%          0%    /sbin/udevd -d
   726    692        root         S <   2184          1%          0%    /sbin/udevd -d
   727    692        root         S <   2184          1%          0%    /sbin/udevd -d
   933        1        root         S      2064           1%          0%    /usr/sbin/thttpd -d /srv/www -p 8080 -
       1        0        root         S      1628           1%          0%    init [5]
   588        2        root      SW            0           0%          0%    [w1_bus_master1]
       5        2        root      SW            0           0%          0%    [kworker/u:0]
   633        2        root      SW            0           0%          0%    [mmcqd/0]
       3        2        root      SW            0           0%          0%    [ksoftirqd/0]

root@am3517-evm:~# cat /proc/interrupts ; ifconfig
           CPU0
11:               0 INTC prcm
12:         1873 INTC DMA
20:               0 INTC gpmc
24: 12114477 INTC can0
25:               2 INTC OMAP DSS
37:     454780 INTC gp timer
56:   1874385 INTC omap_i2c
57:               0 INTC omap_i2c
58:       84972 INTC omap_hdq
61:               0 INTC omap_i2c
71:               1 INTC musb-hdrc.0
72:               0 INTC serial idle
73:               0 INTC serial idle
74:       22509 INTC serial idle, OMAP UART2
77:               0 INTC ehci_hcd:usb2
83:         2765 INTC mmc0
86:     286560 INTC mmc1
160:             0 GPIO tps6507x
162:             1 GPIO mmc1
184:             0 GPIO ds1374
186:             0 GPIO tca8418-keypad
224:             0 GPIO mmc0
Err:              0

can0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
UP RUNNING NOARP MTU:16 Metric:1
RX packets:12732263 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:10
RX bytes:88788609 (84.6 MiB) TX bytes:0 (0.0 B)
Interrupt:24

1 #include <stdio.h>
2 #include <sys/types.h>
3 #include <sys/socket.h>
4 #include <sys/ioctl.h>
5 #include <net/if.h>
6
7 #include <linux/can.h>
8 #include <linux/can/raw.h>
9 #include <string.h>
10
11 /* At time of writing, these constants are not defined in the headers */
12 #ifndef PF_CAN
13 #define PF_CAN 29
14 #endif
15
16 #ifndef AF_CAN
17 #define AF_CAN PF_CAN
18 #endif
19
20 int main(int argc, char *argv[])
21 {
22     /* create a frame */
23     struct can_frame frame;
24     /* interface */
25     struct ifreq ifr;
26     /* number of te */
27     int bytes_read;
28     /* create the socket */
29     int skt = socket( PF_CAN, SOCK_RAW, CAN_RAW );
30     /* socket address */
31     struct sockaddr_can addr;
32     /* counter SFF */
33     unsigned long countSFF;
34     /* counter EFF*/
35     unsigned long countEFF;
36
37     countSFF = 0;
38     countEFF = 0;
39     /* locate the interface you wish to use */
40     strcpy( ifr.ifr_name, "can0" );
41     ioctl( skt, SIOCGIFINDEX, &ifr ); /* ifr.ifr_ifindex gets filled with that device's index */
42     /* select that CAN interface, and bind the socket to it. */
43     addr.can_family = AF_CAN;
44     addr.can_ifindex = ifr.ifr_ifindex;
45     bind( skt, ( struct sockaddr * ) &addr, sizeof( addr ) );
46     while(1)
47     {
48         bytes_read = read( skt, &frame, sizeof( frame ) );
49         if( bytes_read < 0 )
50         {
51             printf( "CAN\n" );
52         }
53         else if ( bytes_read > 0 )
54         {
55             if( !( frame.can_id & 0x80000000U ) )
56             {
57                 countSFF++;
58             }
59             else
60             {
61                 countEFF++;
62             }
63         }
64     }
65
66     return 0;
67 }