RFR (L): JDK-8061308: Remove iCMS

Bengt Rutisson bengt.rutisson at oracle.com
Thu Oct 23 08:41:14 UTC 2014


Thanks for the review Mikael!

Bengt

On 2014-10-23 10:25, Mikael Gerdin wrote:
> Bengt,
>
> On 2014-10-23 09:59, Bengt Rutisson wrote:
>>
>> Hi Mikael,
>>
>> Thanks for looking at this!
>>
>> On 2014-10-22 14:46, Mikael Gerdin wrote:
>>> Hi Bengt,
>>>
>>> On 2014-10-17 13:43, Bengt Rutisson wrote:
>>>>
>>>> Hi everyone,
>>>>
>>>> Can I have a couple of reviews for this change?
>>>>
>>>> HotSpot changes:
>>>> http://cr.openjdk.java.net/~brutisso/8061308/hotspot/
>>>
>>> The following can also be removed:
>>>
>>> src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp: 
>>>
>>>
>>>
>>> CMSStats::_cms_duration_per_mb (only used by
>>> icms_update_duty_cycle_impl and CMSStats::print_on)
>>>
>>> 1040:static inline size_t percent_of_space(Space* space, HeapWord* 
>>> addr)
>>> (only used by allocation_limit_reached and 
>>> icms_update_allocation_limits)
>>>
>>> src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp: 
>>>
>>>
>>>
>>> ConcurrentMarkSweepThread::trace_state(const char* desc)
>>> (only used by icms_wait, {start,stop}_icms)
>>> and its enabling flag CMSTraceThreadState (it's a develop flag)
>>
>> Great that you found this!
>>
>> Here's an updated webrev with your changes and the EdenSpace -> eden
>> changes that Jon found:
>>
>> http://cr.openjdk.java.net/~brutisso/8061308/hotspot.01/
>>
>> Here's the diff compared to the last webrev:
>>
>> http://cr.openjdk.java.net/~brutisso/8061308/hotspot.00-01-diff/
>
> Looks good.
>
> /Mikael
>
>>
>>>
>>> Otherwise the change looks good to me.
>>
>> Thanks!
>>
>> Bengt
>>
>>>
>>>>
>>>> JDK changes:
>>>> http://cr.openjdk.java.net/~brutisso/8061308/jdk/
>>>> (Just a small update to a test library class.)
>>>
>>> Looks good.
>>>
>>> /Mikael
>>>
>>>>
>>>> JBS bug:
>>>> https://bugs.openjdk.java.net/browse/JDK-8061308
>>>>
>>>> The change removes the incremental mode of CMS. This work is part 
>>>> of JEP
>>>> 214 (http://openjdk.java.net/jeps/214). There are quite a few lines
>>>> changed. Mostly it is just removal of code and it should hopefully be
>>>> fairly straight forward to review.
>>>>
>>>> One interesting side effect of removing iCMS was that the 
>>>> ConcEdenSpace
>>>> (a subclass in the Space hierarchy) could be removed. It 
>>>> implemented the
>>>> "soft-end" feature that only iCMS was taking advantage of. When I had
>>>> removed ConcEdenSpace it turned out that its superclass, EdenSpace, 
>>>> was
>>>> actually an unnecessary class that did not add anything so I removed
>>>> that too. When I then went to update the comment in space.hpp that
>>>> describes the Space hierarchy I noticed that the description of the
>>>> hierarchy was completely out-dated. Rather than bringing it 
>>>> up-to-date I
>>>> removed the comment. I think that type of information will only get
>>>> out-dated quickly again and it is much easier to let your IDE 
>>>> create the
>>>> correct type hierarchy view dynamically for you.
>>>>
>>>> Thanks,
>>>> Bengt
>>



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