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Re: Help required with a script


Hi Frank,
Rightly said by you. They do not map to their actual line numbers.


kernel.statement("__migrate_task@kernel/sched.c:6302") /* pc=_stext+0x1995f
*/ /* <- kernel.statement("*@kernel/sched.c:6294") */
printf("\\nError: Process failed to migrate. Destination CPU (CPU %d) is
offline.\\n\\n", _dwarf_tvar_get_dest_cpu_2())
kernel.statement("__migrate_task@kernel/sched.c:6310") /* pc=_stext+0x1997f
*/ /* <- kernel.statement("*@kernel/sched.c:6308") */
printf("\\nTask already migrated to CPU %d\\n\\n",
_dwarf_tvar_get_dest_cpu_4())
kernel.statement("__migrate_task@kernel/sched.c:6313") /* pc=_stext+0x1998b
*/ /* <- kernel.statement("*@kernel/sched.c:6311") */
printf("\\nError: Process failed to migrate to CPU %d. CPU affinity of
current task has changed.", _dwarf_tvar_get_dest_cpu_4())
kernel.statement("__migrate_task@kernel/sched.c:6317") /* pc=_stext+0x1999e
*/ /* <- kernel.statement("*@kernel/sched.c:6317") */
printf("\\nSuccess: Task successfully migrated\\n\\n")


And I found something interesting out of it that, when I try to put a
.statement on a line number, which has a jump/return statement, then it
doesn't map properly in my case. It maps to some line number ahead of the
one actually mentioned.
What could be the issue ?
Frank Ch. Eigler wrote:
> 
> beginner966 <nitin966@gmail.com> writes:
> 
>> [...]  This is the script which I had written to gather information
>> on migration of task to other CPU. I also wanted to report the
>> appropriate errors, so I had used 4 kernel.statement probes. But the
>> problem is that all 4 kernel.statement probes get executed
>> simultaneously, which should not happen according to the original
>> code. [...]
> 
> I suspect we're getting hurt by the statement placement heuristics
> that allow a slight fuzz in line numbers if there is no exact match in
> the debugging info.  Could you run again with --vp 02 to see what PC
> values the various .statement probes end up mapping to?
> 
> 
> - FChE
> 
> 
Quoted from: 
http://www.nabble.com/Help-required-with-a-script-tp21418350p21421478.html


Frank Ch. Eigler wrote:
> 
> beginner966 <nitin966@gmail.com> writes:
> 
>> [...]  This is the script which I had written to gather information
>> on migration of task to other CPU. I also wanted to report the
>> appropriate errors, so I had used 4 kernel.statement probes. But the
>> problem is that all 4 kernel.statement probes get executed
>> simultaneously, which should not happen according to the original
>> code. [...]
> 
> I suspect we're getting hurt by the statement placement heuristics
> that allow a slight fuzz in line numbers if there is no exact match in
> the debugging info.  Could you run again with --vp 02 to see what PC
> values the various .statement probes end up mapping to?
> 
> 
> - FChE
> 
> 

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