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Hi Tony,<br>
<br>
NIce to hear from you! <br>
<br>
<br>
On 18/06/15 00:30, Tony Printezis wrote:<br>
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<blockquote
cite="mid:etPan.5581f51b.699a1ea0.1215a@tw-mbp-tprintezis"
type="cite">
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Hi all,</div>
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">A small patch
for your consideration:</div>
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><a
moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Etonyp/8086056/webrev.0/">http://cr.openjdk.java.net/~tonyp/8086056/webrev.0/</a></div>
</blockquote>
<br>
A couple of style comments:<br>
<br>
891 const size_t MinOldGenCapacity = G;<br>
892 const size_t MaxOldGenCapacity = 16 * G;<br>
893 assert(MinOldGenCapacity <= MaxOldGenCapacity, "sanity");<br>
<br>
Local variables are normmaly named using lower case and underscore.
So, min_old_gen_capacity and max_old_gen_capacity. Same for the rest
of the local variables in
ParNewGeneration::adjust_cards_per_stride().<br>
<br>
Having said that, I think it would be good to turn some of these
constants into flags (which means that the naming should be as it is
now ;) ). Especially since you say that you haven't done much
performance testing of these values. I would prefer that we could
adjust them at runtime. Best would of course be if you could take
the time to do the performance testing.<br>
<br>
I realize that the assert on line 893 might have been useful if you
were playing around with the numbers when you were experimenting
with the patch. But now it looks mostly like line noise to me. Same
with the assert on line 898.<br>
<br>
I would also consider factoring the actual computation out into a
separate helper method.<br>
<br>
I also second Jon's comment on that it would be good with a more
explicit way of turning this feature off.<br>
<br>
Thanks,<br>
Bengt<br>
<br>
<blockquote
cite="mid:etPan.5581f51b.699a1ea0.1215a@tw-mbp-tprintezis"
type="cite">
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">(BTW, for some
reason some of the webrev output is a bit messed up. Not sure
why, maybe some hg incompatibility I guess. The diffs look OK
though. I also attached the patch to this e-mail.)</div>
<div id="bloop_customfont"
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">There’s a bit
of info on the JIRA on the rationale for the patch:</div>
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><a
moz-do-not-send="true"
href="https://bugs.openjdk.java.net/browse/JDK-8086056">https://bugs.openjdk.java.net/browse/JDK-8086056</a></div>
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style="font-family:Helvetica,Arial;font-size:13px; color:
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">The min / max
values for the old gen capacity and ParGCCardsPerStrideChunk
were chosen empircally after running a few (mostly synthetic
tests) on Linux x64. If someone has the cycles to do a more
extensive performance study, I’d be happy to revise them
accordingly.</div>
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Regards,</div>
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rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br>
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<div id="bloop_customfont"
style="font-family:Helvetica,Arial;font-size:13px; color:
rgba(0,0,0,1.0); margin: 0px; line-height: auto;">Tony</div>
<br>
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<div>-----</div>
<div><br>
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<div>Tony Printezis | JVM/GC Engineer / VM Team | Twitter</div>
<div><br>
</div>
<div>@TonyPrintezis</div>
<div><a moz-do-not-send="true"
href="mailto:tprintezis@twitter.com">tprintezis@twitter.com</a></div>
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