<div dir="ltr">We were investigating some features and figured out that ParallelScavange and ParNew has different TenuringTreshold heuristics.<div>We thought it would be nice to have a flag that can control the adaptiveness, so that we can fix it on purpose to isolate other performance factors.</div><div>--Jungwoo</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Mar 9, 2015 at 11:27 AM, Jon Masamitsu <span dir="ltr"><<a href="mailto:jon.masamitsu@oracle.com" target="_blank">jon.masamitsu@oracle.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Jungwoo,<span class=""><br>
<br>
<div>On 03/06/2015 06:03 PM, Jungwoo Ha
wrote:<br>
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<blockquote type="cite">
<div dir="ltr">I think it is the same for all JDK{7,8,9}.
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<div>arguments.cpp disabled UseAdaptiveSizePolicy for CMS.</div>
<div>parallel scavange initializes _tenuring_threshold with</div>
<div> _tenuring_threshold = (UseAdaptiveSizePolicy) ?
InitialTenuringThreshold : MaxTenuringThreshold;</div>
<div>whereas CMS uses</div>
<div> _tenuring_threshold = MaxTenuringThreshold;</div>
<div><br>
</div>
<div>adjust_desired_tenuring_threshold() is called inside
ParNewGeneration::collect(), which calls
compute_tenuring_threshold.</div>
<div>It only uses MaxTenuringThreshold and TargetSurvivorRatio.</div>
<div>I don't see any other flags here.<br>
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Yes, this is the intended behavior.<br>
<br>
You're saying we're sometimes wasting survivor space?<span class="HOEnZb"><font color="#888888"><br>
<br>
Jon</font></span><span class=""><br>
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<blockquote type="cite">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Fri, Mar 6, 2015 at 4:28 PM, Jon
Masamitsu <span dir="ltr"><<a href="mailto:jon.masamitsu@oracle.com" target="_blank">jon.masamitsu@oracle.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">This is in
jdk9?<span><font color="#888888"><br>
<br>
Jon</font></span>
<div>
<div><br>
<br>
On 3/6/2015 4:21 PM, Jungwoo Ha wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On CMS when UseAdaptiveSizePolicy is off, still
tenuring_threshold is being changed.<br>
Is this an intended behavior?<br>
(yes. I know it is not "size" related heuristics)<br>
<br>
It would be nice to have a flag that can disable
adjusting tenuring threshold,<br>
or at least set minimum threshold. When the default
heuristics doesn't work,<br>
there are nothing much we can do other than changing
the Max.<br>
<br>
--Jungwoo<br>
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