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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Hi
</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Michihiro,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Further testing is showing a moderate performance gain with your G1 patch in SPECjbb on AArch64. We haven’t completely pinned the earlier regression on user error on our part,
but it’s looking likely. The new code on AArch64 is looking as relaxed as can be
</span><span style="font-size:11.0pt;font-family:"Segoe UI Emoji",sans-serif">😊</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">Thank you for working on this, and letting us investigate!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
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<span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Derek<o:p></o:p></span></li></ul>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Michihiro Horie [mailto:HORIE@jp.ibm.com]
<br>
<b>Sent:</b> Friday, June 15, 2018 11:44 PM<br>
<b>To:</b> White, Derek <Derek.White@cavium.com><br>
<b>Cc:</b> david.holmes@oracle.com; Gustavo Bueno Romero <gromero@br.ibm.com>; hotspot-gc-dev@openjdk.java.net; Kim Barrett <kim.barrett@oracle.com>; Doerr, Martin <martin.doerr@sap.com><br>
<b>Subject:</b> RE: RFR(M): 8204524: Unnecessary memory barriers in G1ParScanThreadState::copy_to_survivor_space<o:p></o:p></span></p>
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<p><span style="font-size:10.0pt;color:#2F2F2F">Hi Derek,</span><br>
<br>
<span style="font-size:10.0pt;color:#2F2F2F">Thank you for sharing your status of still having inconsistent results with the patch. I would wait for your updates.</span><br>
<br>
<span style="font-size:10.0pt;color:#2F2F2F">Thanks again,</span><br>
<br>
<br>
<span style="font-size:10.0pt">Best regards,</span><br>
<span style="font-size:10.0pt">--</span><br>
<span style="font-size:10.0pt">Michihiro,</span><br>
<span style="font-size:10.0pt">IBM Research - Tokyo</span><br>
<br>
<img width="16" height="16" style="width:.1666in;height:.1666in" id="_x0000_i1025" src="cid:image001.gif@01D4072D.B28F3740" alt="Inactive hide details for "White, Derek" ---2018/06/15 17:55:19---Hi Michihiro, Status update:"><span style="font-size:10.0pt;color:#424282">"White,
Derek" ---2018/06/15 17:55:19---Hi Michihiro, Status update:</span><br>
<br>
<span style="font-size:10.0pt;color:#5F5F5F">From: </span><span style="font-size:10.0pt">"White, Derek" <<a href="mailto:Derek.White@cavium.com">Derek.White@cavium.com</a>></span><br>
<span style="font-size:10.0pt;color:#5F5F5F">To: </span><span style="font-size:10.0pt">Kim Barrett <<a href="mailto:kim.barrett@oracle.com">kim.barrett@oracle.com</a>>, Michihiro Horie <<a href="mailto:HORIE@jp.ibm.com">HORIE@jp.ibm.com</a>></span><br>
<span style="font-size:10.0pt;color:#5F5F5F">Cc: </span><span style="font-size:10.0pt">Gustavo Bueno Romero <<a href="mailto:gromero@br.ibm.com">gromero@br.ibm.com</a>>, "<a href="mailto:david.holmes@oracle.com">david.holmes@oracle.com</a>" <<a href="mailto:david.holmes@oracle.com">david.holmes@oracle.com</a>>,
"<a href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a>" <<a href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a>></span><br>
<span style="font-size:10.0pt;color:#5F5F5F">Date: </span><span style="font-size:10.0pt">2018/06/15 17:55</span><br>
<span style="font-size:10.0pt;color:#5F5F5F">Subject: </span><span style="font-size:10.0pt">RE: RFR(M): 8204524: Unnecessary memory barriers in G1ParScanThreadState::copy_to_survivor_space</span><o:p></o:p></p>
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<br>
<tt><span style="font-size:10.0pt">Hi Michihiro,</span></tt><span style="font-size:10.0pt;font-family:"MS Gothic""><br>
<br>
<tt>Status update:</tt><br>
<tt>My colleague and I are getting inconsistent results with this patch: -23% to +7% on SPECjbb, so we're trying to verify what's going on.</tt><br>
<br>
<tt>On an unrelated note, the aarch64 port relies on GCC's __atomic_compare_exchange to implemented the relaxed case of Atomic::PlatformCmpxchg, and gcc 6 and earlier sometimes do a poor job on it. Not enough to account for the numbers we saw though.</tt><br>
<br>
<tt>I hope to have an answer by Monday.</tt><br>
<br>
<tt>- Derek</tt><br>
<br>
<tt>> -----Original Message-----</tt><br>
<tt>> From: hotspot-gc-dev [<a href="mailto:hotspot-gc-dev-bounces@openjdk.java.net">mailto:hotspot-gc-dev-bounces@openjdk.java.net</a>]</tt><br>
<tt>> On Behalf Of Kim Barrett</tt><br>
<tt>> Sent: Wednesday, June 13, 2018 5:16 PM</tt><br>
<tt>> To: Michihiro Horie <<a href="mailto:HORIE@jp.ibm.com">HORIE@jp.ibm.com</a>></tt><br>
<tt>> Cc: Gustavo Bueno Romero <<a href="mailto:gromero@br.ibm.com">gromero@br.ibm.com</a>>;</tt><br>
<tt>> <a href="mailto:david.holmes@oracle.com">david.holmes@oracle.com</a>; <a href="mailto:hotspot-gc-dev@openjdk.java.net">
hotspot-gc-dev@openjdk.java.net</a></tt><br>
<tt>> Subject: Re: RFR(M): 8204524: Unnecessary memory barriers in</tt><br>
<tt>> G1ParScanThreadState::copy_to_survivor_space</tt><br>
<tt>> </tt><br>
<tt>> External Email</tt><br>
<tt>> </tt><br>
<tt>> > On Jun 7, 2018, at 2:01 AM, Michihiro Horie <<a href="mailto:HORIE@jp.ibm.com">HORIE@jp.ibm.com</a>> wrote:</tt><br>
<tt>> ></tt><br>
<tt>> > Dear all,</tt><br>
<tt>> ></tt><br>
<tt>> > Would you please review the following change?</tt><br>
<tt>> ></tt><br>
<tt>> > Bug: <a href="https://bugs.openjdk.java.net/browse/JDK-8204524">https://bugs.openjdk.java.net/browse/JDK-8204524</a></tt><br>
<tt>> > Webrev: <a href="http://cr.openjdk.java.net/~mhorie/8204524/webrev.00">http://cr.openjdk.java.net/~mhorie/8204524/webrev.00</a></tt><br>
<tt>> </tt><br>
<tt>> I was going to say that this looks good to me.</tt><br>
<tt>> </tt><br>
<tt>> But then I saw Derek White’s reply about an unexpected performance</tt><br>
<tt>> regression.</tt><br>
<tt>> I’d like to wait until he reports back.</tt><br>
<br>
<br>
</span><br>
<br>
<o:p></o:p></p>
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