Top syscalls

[Hien Nguyen <hien at us dot ibm dot com>]

This script will list the top 20 system calls during the interval of 
2000 jiffies contineuosly. Run this script  with the latest systemtap 
from CVS. To run the script
stap -g topsys.stp

It takes a while for the system compiling the module, so be patient. The 
output would look like this

SYSCALL                                                 COUNT
sys_gettimeofday                                        191
sys_ioctl                                               67
sys_poll                                                67
sys_read                                                54
sys_select                                              50
sys_setitimer                                           43
sys_write                                               27
sys_sigreturn                                           21
sys_stat64                                              7
sys_lstat64                                             5
sys_rt_sigprocmask                                      4
sys_time                                                2
sys_rt_sigaction                                        1
sys_wait4                                               1
sys_exit_group                                          1
sys_exit                                                1
sys_waitpid                                             1
sys_fstat64                                             1
sys_writev                                              1
sys_open                                                1
----------------------------------------------------------------


Note: In order fro this script to run contineuosly I have to reset 
CONTEXT->actioncount every time I print the list, which breaks Frank's 
safety measure, otherwise I would get this error

ERROR: MAXACTION exceeded near identifier 'sys_cnt' at topsys.stp:33:3

I guess if you are running a script in guru mode such action is allowed.

Hien.
#! stap

global syscall_count, syscall_name

function syscall_name:string () %{
	char *str, buff[80];
	char *tok;
	str = buff;
	strlcpy(str, CONTEXT->probe_point, sizeof(buff));
	tok = strsep(&str, "\"");
	tok = strsep(&str, "@");
	sprintf(str, "%-25s", tok);
	strlcpy(THIS->__retvalue, str, MAXSTRINGLEN);
%}

function reset_maxaction () %{
	if (CONTEXT && CONTEXT->actioncount)
		CONTEXT->actioncount=0;
%}
	
function accumulate () {
	syscall=syscall_name()
	syscall_count[syscall]++
	# I use this array to reference to syscall_count array in reset_count 
	syscall_name[syscall]=0	 
}


function print_top () {
	lcnt=0
	reset_maxaction ()
	foreach ([syscall] in syscall_count) {
		sys_cnt = syscall_count[syscall]
		if (sys_cnt > lcnt) {
 			lsyscall = syscall
			lcnt = sys_cnt
		}
	}
	if (lcnt > 0) 
		log (lsyscall . "\t\t\t\t" . string(lcnt))
	else 
		print ("\n");
	syscall_count[lsyscall]=0
}

function reset_syscall_count () {
	foreach ([syscall] in syscall_name) 
		syscall_count[syscall] = 0
}

function print_systop () {
	log ("SYSCALL                  \t\t\t\tCOUNT")
	for (line=0; line<20; line++)
		print_top()
	reset_syscall_count ()
}
 
function get_daemon_pid:long () 
%{
	THIS->__retvalue = _stp_pid;
%}

probe kernel.function("sys_*") {
	if (pid() != get_daemon_pid())
		accumulate ()
}

probe timer.jiffies(2000) {
	print_systop ()
	log("--------------------------------------------------------------")
}