poll
,
select
,
epoll
,
itimer
,
futex
,
nanosleep
, and
signal
).
However, in some systems, an excessive number of system calls
outside that small subset
might be responsible for time spent in the
kernel. If you suspect that an application is using
system calls excessively, you need to
identify the most frequently used system calls on the
system. To do this, use topsys.stp.
#! /usr/bin/env stap # # This script continuously lists the top 20 systemcalls in the interval # 5 seconds # global syscalls_count probe syscall.* { syscalls_count[name] <<< 1 } function print_systop () { printf ("%25s %10s\n", "SYSCALL", "COUNT") foreach (syscall in syscalls_count- limit 20) { printf("%25s %10d\n", syscall, @count(syscalls_count[syscall])) } delete syscalls_count } probe timer.s(5) { print_systop () printf("--------------------------------------------------------------\n") }
Example 5.17. topsys.stp Sample Output
-------------------------------------------------------------- SYSCALL COUNT gettimeofday 1857 read 1821 ioctl 1568 poll 1033 close 638 open 503 select 455 write 391 writev 335 futex 303 recvmsg 251 socket 137 clock_gettime 124 rt_sigprocmask 121 sendto 120 setitimer 106 stat 90 time 81 sigreturn 72 fstat 66 --------------------------------------------------------------