Re: [rvm-research] Regarding Address of Object Reference in Field section of Object

[Hari K. <hk...@ti...>]

Robin,

I figured out that in one of the read barrier inline method, I used writeln
method which caused that issue. Thank you for your help.


On Tue, Jan 14, 2014 at 10:46 PM, Hari Krishnan <hk...@ti...>wrote:

> Robin,
>
> I realize that when I download a new version of repo and build it, it
> builds and the poisoned BaseBase works perfectly. I have to carefully see
> the changes in my code. But the diff  is potentially showing no changes
> that affects the poisoned plan. It is strange. I will get back to you after
> I find what is the issue. Thank you very much Robin for your help.
>
> Cheers
> Hari Krishnan
>
>
> On Tue, Jan 14, 2014 at 5:12 PM, Robin Garner <rob...@gm...>wrote:
>
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>> The Poisoned collector in current hg tip works for me in BaseBase,
>> FullAdaptive and FastAdaptive configurations, at least for the handful
>> of dacapo 2006 benchmarks I looked at.
>>
>> The Poisoned heap collector is also included in the nightly sanity
>> checks, and gets 98%+ success, so odds are its either a stray change
>> in your code base or something to do with your environment.
>>
>> Which version of JikesRVM are you building ?  What environment ?  What
>> benchmark are you running ? Can you double-check that there are no
>> changes to the code base, and do a fresh build ?
>>
>> cheers
>> Robin
>>
>> On 14/01/14 18:18, Hari Krishnan wrote:
>> > Rifat,
>> >
>> > The seg fault is thrown for poisoned implementation also. Not just
>> > for my implementation. I hope you can let me know why  this is
>> > happening. Thank you.
>> >
>> >
>> > On Tue, Jan 14, 2014 at 12:55 AM, Hari Krishnan
>> > <hk...@ti... <mailto:hk...@ti...>> wrote:
>> >
>> > Rifat,
>> >
>> > When I add in the constraints class to return true for the
>> > specified method, the rvm when executing is giving a seg fault.
>> >
>> >
>> > Cheers Hari
>> >
>> >
>> > On Tue, Jan 14, 2014 at 12:16 AM, Rifat Shahriyar
>> > <rif...@an... <mailto:rif...@an...>>
>> > wrote:
>> >
>> > You need to set the constraint needsObjectReferenceReadBarrier() to
>> > true. Look at PoisonedConstraints.
>> >
>> > Regards - Rifat
>> >
>> >
>> > On 14/01/2014 5:11 pm, Hari Krishnan wrote:
>> >> Robin,
>> >>
>> >> Thank you. I am looking at that code.  When I override
>> >> objectReferenceRead it seems like it is never called. I am trying
>> >> to understand how it works. Is there anything I have to do other
>> >> than overriding that in my mutator class?
>> >>
>> >> Cheers Hari Krishnan.
>> >>
>> >>
>> >> On Mon, Jan 13, 2014 at 11:47 PM, Robin Garner
>> >> <rob...@gm... <mailto:rob...@gm...>> wrote:
>> >>
>> > The MMTk plan "poisoned" unconditionally sets and clears the
>> > low-order bit of all object references - this is the regression
>> > test for object read and write barriers.
>> >
>> > cheers
>> >
>> > On 14/01/14 15:53, Hari Krishnan wrote:
>> >> Robin,
>> >
>> >> The process is basically to mark the references as I
>> > trace the
>> >> objects. Since I want to mark the instance field
>> > references in each
>> >> object, I want to mutate a single bit indicating the
>> > reference is
>> >> processed.  So yes to question (you want to add a single
>> > bit of
>> >> metadata to each object reference ?).Thank you for your
>> > help. I
>> >> want to try Read Barriers. I appreciate your quick
>> > response. Is
>> >> there any code that  already overrides read barrier?
>> >
>> >> Cheers Hari Krishnan.
>> >
>> >
>> >> On Mon, Jan 13, 2014 at 10:45 PM, Robin Garner
>> >> <rob...@gm... <mailto:rob...@gm...>
>> > <mailto:rob...@gm... <mailto:rob...@gm...>>>
>> > wrote:
>> >
>> >> Hari,
>> >
>> >> Just to clarify, you want to add a single bit of
>> > metadata to each
>> >> object reference ?
>> >
>> >> The "simplest"[1] solution is to use one of the two
>> > low-order bits
>> >> of each object reference (objects are always (at least)
>> > 4-byte
>> >> aligned). In order to do this you'll need a read barrier
>> > that masks
>> >> out this bit so that the mutator always sees aligned
>> > pointers, and
>> >> a write barrier that reinstates the metadata.
>> >
>> >> Alternatively, if this is too expensive, I'd suggest adding
>> >> additional space to the object via the classloader - how
>> > easy this
>> >> is depends on how you want to use the data, how much
>> > space you're
>> >> prepared to use etc.
>> >
>> >> cheers
>> >
>> >> [1] Read barriers are never simple :-/
>> >
>> >> On 14/01/14 12:01, Hari Krishnan wrote:
>> >>> Hi ,
>> >
>> >>> I want to set a bit, toggle a bit and test a bit in the
>> > section
>> >>> where each address of the instance field (object
>> > references)
>> >>> saved in objects. Is there any bit that I can use in
>> > each object
>> >>> fields for this purpose?
>> >
>> >>> Cheers Hari Krishnan
>> >
>>
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