<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><br><br>ysr1729</div><div><br>On May 7, 2015, at 12:25, Jon Masamitsu <<a href="mailto:jon.masamitsu@oracle.com">jon.masamitsu@oracle.com</a>> wrote:<br><br></div><blockquote type="cite"><div>
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Ramki,<br>
<br>
Did you ever make ParNew depth-first copying?<br>
<br></div></blockquote><div><br></div>No, I didn't ever get around to it, as far as I recall... <div><br></div><div>-- ramki</div><div><br><blockquote type="cite"><div>
Jon<br>
<br>
<div class="moz-cite-prefix">On 05/07/2015 11:51 AM, Jon Masamitsu
wrote:<br>
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<br>
<br>
<div class="moz-cite-prefix">On 05/06/2015 07:56 PM, Tangwei
(Euler Architecture & Design Dept) wrote:<br>
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<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Would
you help to list the object copying policy for different
GC? Or pointing out where to find such information? </span></p>
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<br>
For the most part UseParallelGC and UseG1GC has depth-first
copying. UseConcMarkSweepGC <br>
and UseSerialGC use breadth-first. I qualify that because I've
heard people argue about whether<br>
that's 100% true.<br>
<br>
Jon<br>
<br>
<blockquote cite="mid:C8D1E566CC4CA845813731FB6FD5C5300108B897@SZXEMI503-MBX.china.huawei.com" type="cite">
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<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">Regards!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US">wei<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D" lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="text-align:left" align="left"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext" lang="EN-US">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext" lang="EN-US"> hotspot-gc-dev [<a moz-do-not-send="true" class="moz-txt-link-freetext" href="mailto:hotspot-gc-dev-bounces@openjdk.java.net">mailto:hotspot-gc-dev-bounces@openjdk.java.net</a>]
<b>On Behalf Of </b> Jon Masamitsu<br>
<b>Sent:</b> Thursday, May 07, 2015 8:23 AM<br>
<b>To:</b> <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a><br>
<b>Subject:</b> Re: Depth first object copying for all
GC?<o:p></o:p></span></p>
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<p class="MsoNormal" style="text-align:left" align="left"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US"><o:p> </o:p></span></p>
<div>
<p class="MsoNormal"><span lang="EN-US">On 5/6/2015 4:34 AM,
Tangwei (Euler Architecture & Design Dept) wrote:<o:p></o:p></span></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span lang="EN-US">Hi All, <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> As a newbie in GC,
I found some discussion on object copying order in
following slides: breadth vs. depth. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It mentioned that <i>“Any
static policy will hurt some applications and help
others”. </i>After searching, there is a BZ shows <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">the object copying
order has been switched from breadth to depth for
ParallelGC in OpenJDK, please correct if I am wrong. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Anyone can help to
confirm if all GC in OpenJDK use depth first copying
now? <o:p></o:p></span></p>
</blockquote>
<p class="MsoNormal" style="text-align:left" align="left"><span style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><br>
No, not all the GC's use depth first copying.<br>
<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Is there any
performance consideration to choose depth first instead of
controlling by option?<o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:left" align="left"><span style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><br>
Yes, there is a performance cost to optionally using
depth-first or breadth-first.<br>
ParallelGC used to have such an option. It made the code
harder to maintain and,<br>
as far as I can recall, there was very little use of the
option. We removed the<br>
it. I recall maybe 1 complaint about it.<br>
<br>
Jon<br>
<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><a moz-do-not-send="true" href="http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf">http://www.oracle.com/technetwork/server-storage/ts-6434-159339.pdf</a><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial","sans-serif"" lang="EN-US"><a moz-do-not-send="true" href="https://bugs.openjdk.java.net/browse/JDK-6450584">https://bugs.openjdk.java.net/browse/JDK-6450584</a>:
Improve object copying order in parallel scavenge</span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Regards!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">wei <o:p></o:p></span></p>
<p class="MsoNormal" style="text-align:left" align="left"><span style="font-size:12.0pt;font-family:"Times New
Roman","serif"" lang="EN-US"><o:p> </o:p></span></p>
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