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List:       openjdk-hotspot-gc-dev
Subject:    Re: RFR: 8205676: ZGC: Remove TLAB allocations in relocation path
From:       Per Liden <per.liden () oracle ! com>
Date:       2018-06-27 14:43:27
Message-ID: 23eadb7e-4074-f728-01b6-1e1e72571465 () oracle ! com
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Thanks Erik!

/Per

On 2018-06-26 18:05, Erik Österlund wrote:
> Hi Per,
> 
> Looks good.
> 
> Thanks,
> /Erik
> 
> On 2018-06-26 12:45, Per Liden wrote:
>> During Java-thread aided relocation, ZGC tries to use the TLAB to 
>> allocate the new object. However, this interacts badly with JEP 331: 
>> Low-Overhead Heap Profiling, as it distorts the profiling statistics. 
>> I propose we remove the use of the TALB in the relocation path, 
>> essentially changing a thread-local pointer bump to a uncontended 
>> CPU-local CAS.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8205676
>> Webrev: http://cr.openjdk.java.net/~pliden/8205676/webrev.0
>>
>> Testing: Currently running benchmarks to verify that this has no 
>> unexpected performance hit.
>>
>> I've filed two follow up RFEs (also out for review now), to clean up 
>> some functions that are now unused:
>> https://bugs.openjdk.java.net/browse/JDK-8205678
>> https://bugs.openjdk.java.net/browse/JDK-8205679
>>
>> /Per
> 
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