<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">New webrev that covers all the suggestions:</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><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 href="http://cr.openjdk.java.net/~tonyp/8086056/webrev.1/">http://cr.openjdk.java.net/~tonyp/8086056/webrev.1/</a></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">(and I also found a version of hg that works OK with webrev; thanks to Jon Masa for the help)</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">I’m not really happy with the way I deal with the 32-bit case. Better suggestions are welcome. Also, I’m not attached to what the cmd line args are called. Better suggestions on that are welcome too.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div><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><p class="airmail_on" style="color:#000;">On June 23, 2015 at 12:19:12 PM, Tony Printezis (<a href="mailto:tprintezis@twitter.com">tprintezis@twitter.com</a>) wrote:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div></div><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;">
Hi Bengt,</div>
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<br></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
I’ll try factoring out the interpolation and tell me what you
think. Sorry, I’m a bit behind on this as I’ve been busy with a
couple of more urgent tasks hee. I’ll get this done shortly.</div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
<br></div>
<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>
<p class="airmail_on" style="color:#000;">On June 22, 2015 at
3:36:10 AM, Bengt Rutisson (<a href="mailto:bengt.rutisson@oracle.com">bengt.rutisson@oracle.com</a>)
wrote:</p>
<blockquote type="cite" class="clean_bq">
<div bgcolor="#FFFFFF" text="#000000">
<div><span><br>
Hi Tony,<br>
<br>
I agree with your comments. Thanks for fixing this!<br>
<br>
One answer at the end of this message...<br>
<br></span>
<div class="moz-cite-prefix"><span>On 2015-06-18 15:50, Tony
Printezis wrote:<br></span></div>
<blockquote cite="mid:etPan.5582cc8d.1bcb7375.1215a@tw-mbp-tprintezis" type="cite">
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
<span>Hi Bengt,</span></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
<span><br></span></div>
<div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">
<span>Thanks for looking at it. Inline.</span></div>
<span><br></span>
<p class="airmail_on" style="color:#000;"><span>On June 18, 2015 at
3:02:45 AM, Bengt Rutisson (<a moz-do-not-send="true" href="mailto:bengt.rutisson@oracle.com">bengt.rutisson@oracle.com</a>)
wrote:</span></p>
<div>
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<div class="moz-cite-prefix"><span><span><br>
Hi Tony,<br>
<br>
NIce to hear from you!<br>
<br>
<br>
On 18/06/15 00:30, Tony Printezis wrote:<br></span></span></div>
<blockquote cite="mid:etPan.5581f51b.699a1ea0.1215a@tw-mbp-tprintezis" type="cite">
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>Hi all,</span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>A small patch for your consideration:</span></div>
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<span><br></span></div>
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<span><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></span></div>
</blockquote>
<span><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.<span class="Apple-converted-space"> </span></span></div>
</div>
</blockquote>
</div>
<p><br></p>
<p>Yeah, I of course usually do that. But as they are constants I
thought I’d make them look like constants. :-)</p>
<p><br></p>
<div>
<div>
<div>
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<div><span>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 ;) ).<span class="Apple-converted-space"> </span></span></div>
</div>
</blockquote>
</div>
<p><br></p>
<p>Hang on! Are you and Masa encourating me to add 5 (!!!) more cmd
line args to HotSpot? ;-)</p>
<p><br></p>
<div>
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<div><span>Especially since you say that you haven't done much
performance testing of these values.</span></div>
</div>
</blockquote>
</div>
</div>
<p><br></p>
<p>To be clear: I did performance testing with chunks sizes in the
256-8k range and with three old gen sizes (2g, 10g, and 20g) and
auto-tuning comes pretty close to optimal; I have numbers on the
JIRA. But, yes, that was only with a couple of (synthetic) tests
and only on one architecture (Linux/x64). If someone there could
try this on a couple more apps and maybe on sparc, as we don’t
happen to have any sparc boxes lying around :-), it’d be
helpful.</p>
<p>But, yes, your suggestion of making the chunk size / old gen
capacity limits into cmd line args definitely makes sense and I had
also considered that myself. But I had decided against it as I
thought you wouldn’t want more cmd line args. :-) How about:</p>
<p>+UseDynamicParGCStrides</p>
<p>DynamicParGCStrides{Min,Max}OldGenCapacity</p>
<p>DynamicParGCStrides{Min,Max}Size</p>
<p>I should also make them all manageable.</p>
<p><br></p>
<div>
<div>
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<div bgcolor="#FFFFFF" text="#000000">
<div><span><span class="Apple-converted-space"> </span>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.</span></div>
</div>
</blockquote>
</div>
<p><br></p>
<p>So, as I said earlier, I did. The numbers are on the JIRA. Is
there anything else I could maybe run? Maybe larger old gen than
20g? (but that’s reaching the memory limits of my workstation,
FWIW)</p>
<p><br></p>
<div>
<div>
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<div><span><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.</span></div>
</div>
</blockquote>
</div>
<p><br></p>
<p>Actually, it as basically stating the invariant for those
parameters (in case someone wants to play around with them). But if
we make the constants into cmd line args this will go away...</p>
<p><br></p>
<div>
<div>
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<div bgcolor="#FFFFFF" text="#000000">
<div><span><br>
I would also consider factoring the actual computation out into a
separate helper method.</span></div>
</div>
</blockquote>
</div>
<p><br></p>
<p>You mean the interpolation? Like:</p>
<p>(base_min, base_max, value_min, value_max, value) -> result
in range [base_min, base_max]?</p>
</div>
</div>
</div>
</div>
</blockquote>
<br>
Yes, that's what I meant. But if you, as suggested above, get rid
of most (all?) of the constant definitions in
adjust_cards_per_stride() then I guess it is mostly only the
interpolation left. So, in that case it may not be necessary to
factor it out. I would have to see a new webrev to have more
comments.<br>
<br>
Thanks,<br>
Bengt<br>
<br>
<blockquote cite="mid:etPan.5582cc8d.1bcb7375.1215a@tw-mbp-tprintezis" type="cite">
<div>
<div>
<div>
<div>
<p>Tony</p>
<p><br></p>
<div>
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<div bgcolor="#FFFFFF" text="#000000">
<div><span><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></span>
<blockquote cite="mid:etPan.5581f51b.699a1ea0.1215a@tw-mbp-tprintezis" type="cite">
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<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>(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.)</span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>There’s a bit of info on the JIRA on the rationale for the
patch:</span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span><a moz-do-not-send="true" href="https://bugs.openjdk.java.net/browse/JDK-8086056">https://bugs.openjdk.java.net/browse/JDK-8086056</a></span></div>
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<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>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.</span></div>
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<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>Regards,</span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span><br></span></div>
<div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; color: rgb(0, 0, 0); margin: 0px;">
<span>Tony</span></div>
<span><br></span>
<div id="bloop_sign_1434579909530055936" class="bloop_sign">
<div style="font-family: helvetica, arial; font-size: 13px;">
<div><span>-----</span></div>
<div><span><br></span></div>
<div><span>Tony Printezis | JVM/GC Engineer / VM Team |
Twitter</span></div>
<div><span><br></span></div>
<div><span>@TonyPrintezis</span></div>
<div><span><a moz-do-not-send="true" href="mailto:tprintezis@twitter.com">tprintezis@twitter.com</a></span></div>
<div><span><br></span></div>
</div>
</div>
</blockquote>
<span><br></span></div>
</div>
</blockquote>
<br class="Apple-interchange-newline"></div>
<br class="Apple-interchange-newline"></div>
<br class="Apple-interchange-newline"></div>
<br class="Apple-interchange-newline"></div>
<br class="Apple-interchange-newline"></div>
<div id="bloop_sign_1434634117464453888" class="bloop_sign">
<div style="font-family:helvetica,arial;font-size:13px">
<div>-----</div>
<div><br></div>
<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>
<div><br></div>
</div>
</div>
</blockquote>
<br></div>
</div>
</blockquote>
<div id="bloop_sign_1435076298751951872" class="bloop_sign">
<div style="font-family:helvetica,arial;font-size:13px">
<div>-----</div>
<div><br></div>
<div>Tony Printezis | JVM/GC Engineer / VM Team | Twitter</div>
<div><br></div>
<div>@TonyPrintezis</div>
<div><a href="mailto:tprintezis@twitter.com">tprintezis@twitter.com</a></div>
<div><br></div>
</div>
</div>
</div></div></span></blockquote> <div id="bloop_sign_1435171154189988096" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px"><div>-----</div><div><br></div><div>Tony Printezis | JVM/GC Engineer / VM Team | Twitter</div><div><br></div><div>@TonyPrintezis</div><div><a href="mailto:tprintezis@twitter.com">tprintezis@twitter.com</a></div><div><br></div></div></div></body></html>