Re: opjitconv runs indefinitely

On 07.05.2015 18:45, Andrew Haley wrote:
> On 05/07/2015 05:34 PM, William Cohen wrote:
>> On 05/07/2015 12:08 PM, Andrew Haley wrote:
>>> On 05/07/2015 04:04 PM, Daniel Hansel wrote:
>>>> in that case these zero sized samples must not be invalidated without any further investigation.
>>>>
>>>> Could you describe such a case where zero-sized samples will be generated?
>>>> Maybe I could figure out how such samples could be used to produce a correct profiling report.
>>>
>>> Surely Oprofile generates the samples.  I have no idea how samples
>>> could be generated against a zero-length region.  Zero-length
>>> regions are perfectly legitimate.
>>
>> I think the question was in reference to earlier email's:
>>
>>   This is a particular PPC thing which generates zero-sized stubs in some cases.
>>
>> There is a thread discussing this problem on the ppc-aix-port-dev mailing list:
>>
>> http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-July/002045.html
>>
>> There seems to be some question whether jvmti should be generating that:
>>
>> http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-July/002048.html
>> https://bugs.openjdk.java.net/browse/JDK-8049441
>>
>> It looks like there is a patch to remove the zero-length regions.
>>
>> However, oprofile should be more graceful in how it handles this.
> 
> Of course it should.  Zero is not a special number: it's a very ordinary
> number.  Some code regions are zero in size.  This is not a Java thing; it
> could happen anywhere.  I can't see any point oprofile resisting this bug
> fix, if only for robustness.
> 
> Andrew.
> 
> 

Hi Andrew and William,

my point is not to resist this bug fix but to understand the scenario(s)
when zero-sized regions could be reported via JVMTI.

And yes ... Oprofile should handle these cases more gracefully.

William, thank you for the links to the mailing list.
Hopefully I could get the necessary information there and could figure out
how to implement a good handling of zero-sized regions.

-- 

Mit freundlichen Grüßen / Kind regards
Daniel Hansel

IBM Deutschland Research & Development GmbH
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Geschäftsführung: Dirk Wittkopp
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