On Fri, Feb 12, 2016 at 03:57:59PM +0000, Mahmood Naderan via dtrace-discuss wrote: > Hello,I use a script to measure the system calls counts as well as their run > time. Thank to Jim Mauro, you can see the script at > https://www.mail-archive.com/dtrace-discuss@lists.dtrace.org/msg00004.html > Problem is recently, I have noticed that the accumulation of reported > syscalls time (in micro second) is strange. See this output: > bash-3.00# su > Feb 29 22:40:12 server su: 'su root' succeeded for root on /dev/console > # kill -CONT 1036 > # ./sc.d -p 1036 > dtrace: 41866 dynamic variable drops with non-empty dirty list > dtrace: 50990 dynamic variable drops with non-empty dirty list > ^C > dtrace: 26719 dynamic variable drops with non-empty dirty list > SYSCALL COUNT TIME(us) > fdsync 3 322593 > rename 4 112 > stat 11 18 > lwp_mutex_wakeup 15 78 > mprotect 23 396 > pollsys 58 2040311 > lwp_sigmask 117 349 > setcontext 117 454 > lwp_park 320 8525843 > lwp_mutex_timedlock 364 2030 > yield 725 568670 > write 6737 45526 > open 27491 353860 > fcntl 27506 54801 > close 27529 54292 > lwp_cond_signal 48837 152506 > lwp_cond_wait 48891 616603479 > lseek 58049 113307 > send 72409 267314 > read 126334 29247492 > fstat 127719 254078 > > # date > Wed Feb 29 22:40:17 EST 2012 > # > ? > As you can see time of running su was 22:40:12 and the time at the > exit point? was 22:40:17. That means the dtrace ran for about 5 > seconds. However, if you sum up the micro seconds, you will see > 658,607,509 us which is about 658 seconds. > > Isn't that strange for you? If you think I am mistaking somewhere, > please let me know. Otherwise, I will explain with more details later.
Given that there are calls to lwp_park() and lwp_* calls, this is clearly a multi-threaded program. So it's easy to imagine that ~100 threads or more could give you these results. Cheers, - jonathan ------------------------------------------- dtrace-discuss Archives: https://www.listbox.com/member/archive/184261/=now RSS Feed: https://www.listbox.com/member/archive/rss/184261/25769126-e243886f Modify Your Subscription: https://www.listbox.com/member/?member_id=25769126&id_secret=25769126-8d47a7b2 Powered by Listbox: http://www.listbox.com
