dtrace discuss - Mar 2007 - about use dtrace analyze tomcat''s situation

everyone Here:
                  How do you do!
   
  dtrace is interesting. I am studing how to write dtrace script and analyze
situation.
I read dtrace_example.pdf and 819-6959.pdf document more than five times with
careful.
because I am newbie to studing dtrace.so I still don''t know how to
begin.
  for question:
  1. What consumes time?
2. Which system call(s) consume(s) time?
---------------------------------------------
  from document dtrace_example.pdf I find follow D script
vi sctime.d
syscall:::entry
/pid == $target/
{
   self->ts = timestamp;
}
syscall:::return
/self->ts/
{
   ela = timestamp - self->ts;
   @tot[probefunc] = sum(ela);
}
  END
{
   normalize(@tot, 1000);
   printa("%12s %@12u\n", @tot);
}
  get Tomcat''s pid :
$ ps -ef | grep tomcat
  tomcat   249     7   0 12:08:02 console     0:01 -sh
  tomcat 12475 12474   0 18:12:15 pts/3       0:00 ps -ef
  tomcat   634     1   0 12:08:14 ?          13:19 /usr/j2sdk1.4.2_04/bin/java
-XX:MaxPermSize=256m -Xms512m -Xmx768m -Djava.awt.h
  tomcat 10324 10321   0 17:37:36 pts/3       0:00 -sh
  tomcat 12474 10324   0 18:12:15 pts/3       0:00 grep tomcat
$ 
   
  # dtrace -s ./sctime.d -p 634
dtrace: script ''./sctime.d'' matched 457 probes
^C
CPU     ID                    FUNCTION:NAME
  8      2                             :END lwp_cond_signal           67
        bind          271
 lwp_sigmask          282
 getsockname          456
   so_socket          528
     fstat64          714
  setsockopt          843
  setcontext          946
       ioctl          959
lwp_mutex_wakeup         1105
lwp_cond_broadcast         1430
       close         1431
     connect         2503
        fsat         2505
  getdents64         3894
       fcntl         6785
      doorfs         7043
 resolvepath         8684
      access        22627
        send        73748
       write       102515
      stat64       126195
lwp_mutex_timedlock       339137
      accept    273694273
        read    285744641
     pollsys   1213647291
lwp_cond_wait   1553123938
  
can see lwp_cond_wait consume about 1553(s)
        pollsys       consume about 1213(s)
  I want to know what are they doing? but I don''t know how to do....
Hope you can help me !how to analyze this ? Please!Help!
   

 		
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 ??????-3.5G???20M??
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