RFR(XXS): 8157271: Avoid extra copy of NativeCallStack

[Markus Gronlund]

Thanks David.

Markus

-----Original Message-----
From: David Holmes 
Sent: den 19 maj 2016 00:39
To: Markus Gronlund; hotspot-runtime-dev at openjdk.java.net
Subject: Re: RFR(XXS): 8157271: Avoid extra copy of NativeCallStack

Seems like a nice enhancement.

I always find it hard to know/determine when copies of objects will be made. Guess that is why I prefer to work with pointers :)

Thanks,
David

On 19/05/2016 6:40 AM, Markus Gronlund wrote:
> Greetings,
>
>
>
> Minor improvement found when reading up on NMT:
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> Description:
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> Pass through a const NativeCallStack& instead of a copy in:
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> MallocSiteHashtableEntry(const NativeCallStack& stack)
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> and let AllocationSite<MemoryCounter> accomplish the single copy into the _call_site member.
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> Change:
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> # HG changeset patch
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> # User mgronlun
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> # Date 1463598559 -7200
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> #      Wed May 18 21:09:19 2016 +0200
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> # Node ID c806533e436f7a1e3fac38101b766ea3d5a5405b
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> # Parent  da110ff6c0e271ded14b015ec7de2e2f85d58e73
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> [mq]: MallocSiteHashtableEntry
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>
>
> diff --git a/src/share/vm/services/mallocSiteTable.hpp 
> b/src/share/vm/services/mallocSiteTable.hpp
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> --- a/src/share/vm/services/mallocSiteTable.hpp
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> +++ b/src/share/vm/services/mallocSiteTable.hpp
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> @@ -62,7 +62,7 @@
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>   public:
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>    MallocSiteHashtableEntry() : _next(NULL) { }
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> -  MallocSiteHashtableEntry(NativeCallStack stack):
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> +  MallocSiteHashtableEntry(const NativeCallStack& stack):
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>      _malloc_site(stack), _next(NULL) { }
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>    inline const MallocSiteHashtableEntry* next() const {
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> Bug:
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> https://bugs.openjdk.java.net/browse/JDK-8157271
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>
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> Thanks in advance
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> Markus
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>