RFR: 8138705: Kitchen sink stress test fails

[Zhengyu Gu]

Sorry, my bad memory. Forgot the other half of comparisons.

Change look good to me.

-Zhengyu

On 05/23/2016 02:25 PM, Max Ockner wrote:
> Zhengyu,
> I have replied below:
>
> On 5/23/2016 8:34 AM, Zhengyu Gu wrote:
>> Hi Max,
>>
>>
>> On 05/17/2016 03:53 PM, Max Ockner wrote:
>>> Hello,
>>> I have responded to suggestions from Coleen and Zhengyu.
>>>
>>> New webrev: http://cr.openjdk.java.net/~mockner/8138705.02/
>>>  - Removed print statements
>>>  - Added check to break out of loop once we reach the end of the 
>>> region being committed
>>>
>>> Thanks,
>>> Max
>>>
>>> On 5/17/2016 9:06 AM, Zhengyu Gu wrote:
>>>> Hi Max,
>>>>
>>>> I have not done a complete review.
>>>>
>>>> virtualMemoryTracker.cpp:  63 - 88
>>>>
>>>> Is it possible that newly committed region does not overlap, but 
>>>> covers an existing region?
>>>>
>> You did not answer above question. If incoming committed region 
>> covers existing region(s), but does not overlap or adjacent to any 
>> the existing region(s), it will be added as new region.
>
> If a region covers an existing (but not identical) region, then it is 
> an overlapping region. Two regions overlap if they intersect in any 
> way. So this case can not happen.
>
>   inline bool overlap_region(address addr, size_t sz) const {
>     VirtualMemoryRegion rgn(addr, sz);
>     return contain_address(addr) ||
>            contain_address(addr + sz - 1) ||
>            rgn.contain_address(base()) ||
>            rgn.contain_address(end() - 1);
>   }
>
> Sorry that I missed this question.
>
> Thanks,
> Max
>
>> As use cases get complicated, I think that it is simpler to always 
>> delete the region(s), then add.
>>
>>
>> src/share/vm/utilities/linkedlist.hpp
>>
>> Nice catch.
>>
>> -Zhengyu
>>
>>>> The loop can stop when rgn->end_addr >= addr + size
>>>>
>>>> -Zhengyu
>>>>
>>>>
>>>> On 05/13/2016 03:39 PM, Max Ockner wrote:
>>>>> Hello,
>>>>> Please review this fix which allows NMT to handle overlapping 
>>>>> commits.
>>>>>
>>>>> Though it would make sense to uncommit space before committing 
>>>>> over it,  this is not always the way things are done. Kitchensink 
>>>>> encounters some intentional overlapping commits in gc, which 
>>>>> previously would cause NMT to throw an assert. Now, these 
>>>>> overlapping commits are handled by recording an uncommit of the 
>>>>> newly committed region before recording the commit. This 
>>>>> effectively chops any of the already-committed space off of the 
>>>>> existing committed region before adding the new commit.  In order 
>>>>> for this all to work, 
>>>>> ReservedMemoryRegion::remove_uncommitted_region was changed to 
>>>>> support uncommitting an arbitrary region. The target behavior of 
>>>>> this operation is to truncate (or split) committed regions which 
>>>>> overlap with the region being uncommitted, while only subtracting 
>>>>> from the total the amount of memory which was actually cleared.
>>>>>
>>>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8138705
>>>>> Webrev: http://cr.openjdk.java.net/~mockner/8138705/
>>>>>
>>>>> Tested with jtreg NMT tests. Survived 72 hours of Kitchensink.
>>>>> Added a test: runtime/NMT/CommitOverlappingRegions.java
>>>>> This test performs various commits and uncommits that overlap in 
>>>>> different ways, and checks that it computes the amount of 
>>>>> committed space correctly.
>>>>>
>>>>> Thanks,
>>>>> Max
>>>>
>>>
>>
>