<html><body><p><font size="2" color="#2F2F2F">Hi Derek</font><font size="2" color="#2F2F2F">,</font><br><br><font size="2" color="#2F2F2F">Thank you for sharing your status of still having inconsistent results with the patch. I would wait for your updates.</font><br><br><font size="2" color="#2F2F2F">Thanks again</font><font size="2" color="#2F2F2F">,</font><br><br><br><font size="2">Best regards,</font><br><font size="2">--</font><br><font size="2">Michihiro,</font><br><font size="2">IBM Research - Tokyo</font><br><br><img width="16" height="16" src="cid:1__=8FBB083DDF87D73D8f9e8a93df938690918c8FB@" border="0" alt="Inactive hide details for "White, Derek" ---2018/06/15 17:55:19---Hi Michihiro, Status update:"><font size="2" color="#424282">"White, Derek" ---2018/06/15 17:55:19---Hi Michihiro, Status update:</font><br><br><font size="2" color="#5F5F5F">From: </font><font size="2">"White, Derek" <Derek.White@cavium.com></font><br><font size="2" color="#5F5F5F">To: </font><font size="2">Kim Barrett <kim.barrett@oracle.com>, Michihiro Horie <HORIE@jp.ibm.com></font><br><font size="2" color="#5F5F5F">Cc: </font><font size="2">Gustavo Bueno Romero <gromero@br.ibm.com>, "david.holmes@oracle.com" <david.holmes@oracle.com>, "hotspot-gc-dev@openjdk.java.net" <hotspot-gc-dev@openjdk.java.net></font><br><font size="2" color="#5F5F5F">Date: </font><font size="2">2018/06/15 17:55</font><br><font size="2" color="#5F5F5F">Subject: </font><font size="2">RE: RFR(M): 8204524: Unnecessary memory barriers in G1ParScanThreadState::copy_to_survivor_space</font><br><hr width="100%" size="2" align="left" noshade style="color:#8091A5; "><br><br><br><tt><font size="2">Hi Michihiro,<br><br>Status update:<br>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.<br><br>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.<br><br>I hope to have an answer by Monday.<br><br> - Derek<br><br>> -----Original Message-----<br>> From: hotspot-gc-dev [</font></tt><tt><font size="2"><a href="mailto:hotspot-gc-dev-bounces@openjdk.java.net">mailto:hotspot-gc-dev-bounces@openjdk.java.net</a></font></tt><tt><font size="2">]<br>> On Behalf Of Kim Barrett<br>> Sent: Wednesday, June 13, 2018 5:16 PM<br>> To: Michihiro Horie <HORIE@jp.ibm.com><br>> Cc: Gustavo Bueno Romero <gromero@br.ibm.com>;<br>> david.holmes@oracle.com; hotspot-gc-dev@openjdk.java.net<br>> Subject: Re: RFR(M): 8204524: Unnecessary memory barriers in<br>> G1ParScanThreadState::copy_to_survivor_space<br>> <br>> External Email<br>> <br>> > On Jun 7, 2018, at 2:01 AM, Michihiro Horie <HORIE@jp.ibm.com> wrote:<br>> ><br>> > Dear all,<br>> ><br>> > Would you please review the following change?<br>> ><br>> > Bug: </font></tt><tt><font size="2"><a href="https://bugs.openjdk.java.net/browse/JDK-8204524">https://bugs.openjdk.java.net/browse/JDK-8204524</a></font></tt><tt><font size="2"><br>> > Webrev: </font></tt><tt><font size="2"><a href="http://cr.openjdk.java.net/~mhorie/8204524/webrev.00">http://cr.openjdk.java.net/~mhorie/8204524/webrev.00</a></font></tt><tt><font size="2"><br>> <br>> I was going to say that this looks good to me.<br>> <br>> But then I saw Derek White’s reply about an unexpected performance<br>> regression.<br>> I’d like to wait until he reports back.<br><br><br></font></tt><br><br><BR>
</body></html>