[dtrace-discuss] Re: timestamp and walltimestamp

[Adam Leventhal]

>  / self->my_traceon && self->my_traceon - timestamp > 6000000000/

I think you want to do 'timestamp - self->my_traceon'. Otherwise you'll get
a big unsigned value.

You're also using the global my_traceon variable in addition to the thread-
local version.

Adam

On Tue, Jan 16, 2007 at 02:45:38PM -0600, rickey c weisner wrote:
> I want to print a stack trace whenever thread 1 for the PID of 
>  interest spends more than 6 seconds in lwp_mutex_timedlock.
>  So I wrote the following:
>  #!/usr/sbin/dtrace -s
>  syscall::lwp_mutex_timedlock:entry
>  / pid == $1 && tid == 1 /
>  {
>  	trace(probefunc);
>  	printf("%Y \n",walltimestamp);
>          self->my_traceon=timestamp;
>  }
>  syscall::lwp_mutex_timedlock:return
>  / self->my_traceon && self->my_traceon - timestamp > 6000000000/
>  {
>  	ustack();
>  }
>  syscall::lwp_mutex_timedlock:return
>  / self->my_traceon /
>  {
>  	trace(probefunc);
>  	printf("%Y \n",walltimestamp);
>          my_traceon=0;
>  }
>  fbt:::
>  / self->my_traceon /
>  {
>  	trace(probefunc);
>  	printf("%Y \n",walltimestamp);
>  }
>  I expect to get an entry from the syscall
>  and entry from fbt ?
>  a stack  from those > 6 sec
>  a return from the syscall.
>  
>  I get as output:
>  The output is like this:
>  0  11028        lwp_mutex_timedlock:entry   lwp_mutex_timedlock
>  2007 Jan 12 10:35:50
>   
>    0  11029       lwp_mutex_timedlock:return   lwp_mutex_timedlock
>  2007 Jan 12 10:35:50
>  
>    0  11028        lwp_mutex_timedlock:entry   lwp_mutex_timedlock
>  2007 Jan 12 10:35:50
>  
>    0  11029       lwp_mutex_timedlock:return
>                libc.so.1`___lwp_mutex_timedlock+0x8
>                libc.so.1`mutex_lock_internal+0x218
>  ... rest of stack
>   0  11029       lwp_mutex_timedlock:return   lwp_mutex_timedlock
>  2007 Jan 12 10:35:50
>  
>  So I got a stack, so the method took longer than 6 seconds, but the
>  walltimestamps between entry and exit show less than a 1 second difference.
>  How can that be ?
>  Plus I get nothing from the fbt probe.
>  
>  rick
> -- 
> 
> Rickey C. Weisner 
> Software Development and Performance Specialist 
> Sun Microsystems, INC
> cell phone: 615-308-1147
> email: rick.weisner at sun.com
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org

-- 
Adam Leventhal, Solaris Kernel Development       http://blogs.sun.com/ahl