dtrace discuss - Aug 2007 - how to access elemets of an arry in dtrace actions

I want to  access some elelmets in an array acoording indexs. 
But,If and  While are  reserverd keys.How to achieve it?
for example:
fbt:::entry
{
     index = 0;
     for (index;index<10;index++)
    {
        printf("%d",g_arry[index]);
    }
}

the only way to add predicate in //.


--
This message posted from opensolaris.org

Hi Liujun:

Just curious why you are using arrays instead of aggregates.
Aggregates are a much better choice in almost all cases, they
have better performance and of course you have printa() that
can print the aggregate without any fancy loop or tricky
predicates.

Also be careful with fbt:::entry - this is over 30,000 probes

Rgds,

Angelo


liujun wrote:
> I want to  access some elelmets in an array acoording indexs. 
> But,If and  While are  reserverd keys.How to achieve it?
> for example:
> fbt:::entry
> {
>      index = 0;
>      for (index;index<10;index++)
>     {
>         printf("%d",g_arry[index]);
>     }
> }
>
> the only way to add predicate in //.
>
>
> --
> This message posted from opensolaris.org
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
>

Thanks Angelo.
I want to trace my kernel module''s global  variable''s
infomation  named g_ModuleArray .It''s an array.

now,My dtrace script is like:

tick-1sec
{

	RdacInfo = upper`g_ModuleArray[0];
               
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);

                RdacInfo = upper`g_ModuleArray[1];
               
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);

                RdacInfo = upper`g_ModuleArray[2];
               
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);
                 ...................
                RdacInfo = upper`g_ModuleArray[n];
               
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);

}

The n index maybe so large that like above to do.


--
This message posted from opensolaris.org

liujun wrote:
> Thanks Angelo.
> I want to trace my kernel module''s global  variable''s
infomation  named g_ModuleArray .It''s an array.
I can''t think of a simple solution to this (I''m assuming that
by "The n
index maybe so large that like above to do" you mean "I don''t
know the
upper bound of *n*").
There''s a good reason that loops aren''t allowed in DTrace: you
can''t
tell at compile-time how often they''re going to run, and this is not 
acceptable by the high standards DTrace adheres to.
The consequence of this is that you need to decide on the upper
"bound"
of your "loop" when you write your script by explicitly putting in 
statements for every "iteration".
(I guess the DTrace native speakers can say this much more 
scientifically ;-)

HTH
Michael
> 
> now,My dtrace script is like:
> 
> tick-1sec
> {
> 
> 	RdacInfo = upper`g_ModuleArray[0];
>                
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);
> 
>                 RdacInfo = upper`g_ModuleArray[1];
>                
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);
> 
>                 RdacInfo = upper`g_ModuleArray[2];
>                
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);
>                  ...................
>                 RdacInfo = upper`g_ModuleArray[n];
>                
printf("%s,%d,%d",RdacInfo->name,RdacInfo->count,RdacInfo->ref);
> 
> }
> 
> The n index maybe so large that like above to do.
> 
> 
> --
> This message posted from opensolaris.org
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org

-- 
Michael Schuster	Sun Microsystems, Inc.
recursion, n: see ''recursion''