1Demonstrations of shmsnoop, the Linux eBPF/bcc version. 2 3shmsnoop traces shm*() syscalls, for example: 4 5# ./shmsnoop.py 6PID COMM SYS RET ARGs 719813 server SHMGET 10000 key: 0x78020001, size: 20, shmflg: 0x3b6 (IPC_CREAT|0666) 819813 server SHMAT 7f1cf8b1f000 shmid: 0x10000, shmaddr: 0x0, shmflg: 0x0 919816 client SHMGET 10000 key: 0x78020001, size: 20, shmflg: 0x1b6 (0666) 1019816 client SHMAT 7f4fd8ee7000 shmid: 0x10000, shmaddr: 0x0, shmflg: 0x0 1119816 client SHMDT 0 shmaddr: 0x7f4fd8ee7000 1219813 server SHMDT 0 shmaddr: 0x7f1cf8b1f000 1319813 server SHMCTL 0 shmid: 0x10000, cmd: 0, buf: 0x0 14 15 16Every call the shm* syscall (SHM column) is displayed 17on separate line together with process info (PID/COMM 18columns) and argument details: return value (RET column) 19and syscall arguments (ARGs column). 20 21The ARGs column contains 'arg: value' couples that represent 22given syscall arguments as described in their manpage. 23 24This works by tracing shm* system calls and sending 25argument details to the python script. 26 27A -T option can be used to include a timestamp column, 28and a -n option to match on a command name. Regular 29expressions are allowed. For example, matching commands 30containing "server" with timestamps: 31 32# ./shmsnoop.py -T -n server 33TIME(s) PID COMM SYS RET ARGs 340.563194000 19825 server SHMDT 0 shmaddr: 0x7f74362e4000 350.563237000 19825 server SHMCTL 0 shmid: 0x18000, cmd: 0, buf: 0x0 36 37 38A -p option can be used to trace only selected process: 39 40# ./shmsnoop.py -p 19855 41PID COMM SYS RET ARGs 4219855 server SHMDT 0 shmaddr: 0x7f4329ff8000 4319855 server SHMCTL 0 shmid: 0x20000, cmd: 0, buf: 0x0 44 45USAGE message: 46# ./shmsnoop.py -h 47usage: shmsnoop.py [-h] [-T] [-p PID] [-t TID] [-d DURATION] [-n NAME] 48 49Trace shm*() syscalls 50 51optional arguments: 52 -h, --help show this help message and exit 53 -T, --timestamp include timestamp on output 54 -p PID, --pid PID trace this PID only 55 -t TID, --tid TID trace this TID only 56 -d DURATION, --duration DURATION 57 total duration of trace in seconds 58 -n NAME, --name NAME only print process names containing this name 59 60examples: 61 ./shmsnoop # trace all shm*() syscalls 62 ./shmsnoop -T # include timestamps 63 ./shmsnoop -p 181 # only trace PID 181 64 ./shmsnoop -t 123 # only trace TID 123 65 ./shmsnoop -d 10 # trace for 10 seconds only 66 ./shmsnoop -n main # only print process names containing "main" 67