<html><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:12px"><div id="yui_3_16_0_1_1436949341245_17908"><span>Hi Thomas,</span></div><div id="yui_3_16_0_1_1436949341245_17909"><span><br></span></div><div dir="ltr" id="yui_3_16_0_1_1436949341245_17911"><span id="yui_3_16_0_1_1436949341245_17910"> Thank a lot for your input! I will go over the articles you mentioned, it seems to be a bit more clear now.</span></div><div dir="ltr" id="yui_3_16_0_1_1436949341245_17912"><span><br></span></div><div dir="ltr" id="yui_3_16_0_1_1436949341245_17913"><span>Thanks</span></div><div dir="ltr" id="yui_3_16_0_1_1436949341245_17913"><span>Ionut Balosin</span></div> <br><div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: verdana, helvetica, sans-serif; font-size: 12px;"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div dir="ltr"> <font size="2" face="Arial"> On Wednesday, July 15, 2015 10:37 AM, Thomas Schatzl <thomas.schatzl@oracle.com> wrote:<br> </font> </div> <br><br> <div class="y_msg_container">Hi Ionut,<br clear="none"><br clear="none">On Tue, 2015-07-14 at 20:12 +0300, ionutb83 wrote:<br clear="none">> Hello All,<br clear="none">> <br clear="none">> <br clear="none">> Could somebody please answer my question below?<br clear="none">> <br clear="none">> <br clear="none">> Best Regards<br clear="none">> Ionut<br clear="none">> <br clear="none">> <br clear="none">> -------- Original message --------<br clear="none">> From: Ionut <br clear="none">> Date:04/07/2015 13:51 (GMT+02:00) <br clear="none">> To: <a shape="rect" ymailto="mailto:hotspot-gc-dev@openjdk.java.net" href="mailto:hotspot-gc-dev@openjdk.java.net">hotspot-gc-dev@openjdk.java.net</a> <br clear="none">> Subject: Dirty Cards Write Barrier <br clear="none">> <br clear="none">> <br clear="none">> Hello Everybody,<br clear="none">><br clear="none">> I have just joined this group and since last year I started to study<br clear="none">> HotSpot more in detail. I have a question for you, so your input will<br clear="none">> be greatly appreciated.<br clear="none">><br clear="none">> Based on my understanding Dirty Cards Write Barrier is a way of<br clear="none">> keeping track of references from Old to Young Generation. This<br clear="none">> technique is used during minor GC to search for objects referred from<br clear="none">> Old generation. <br clear="none">> Is this technique used by all minor GC: Serial, Parallel, Parallel<br clear="none">> Old, CMS, G1?<br clear="none"><br clear="none">All but G1 use this technique to track references between generations.<br clear="none">G1 uses card marking to track references between regions, not<br clear="none">generations. Also the time and place of how these references are<br clear="none">converted into remembered sets (and the use of the extra data structure<br clear="none">to store remembered sets itself) is quite different.<br clear="none"><br clear="none">G1 uses a technique roughly based on what<br clear="none"><br clear="none">David Detlefs, Ross Knippel, William D. Clinger, and Matthias Jacob.<br clear="none">2002. Concurrent Remembered Set Refinement in Generational Garbage<br clear="none">Collection. In Proceedings of the 2nd Java™ Virtual Machine Research and<br clear="none">Technology Symposium, Samuel P. Midkiff (Ed.). USENIX Association,<br clear="none">Berkeley, CA, USA, 13-26. <br clear="none"><br clear="none">describe.<br clear="none"><br clear="none">Note that both G1 and CMS use write barriers for concurrent marking too<br clear="none">(and actually G1 also has a special case where it uses a read barrier).<div class="yqt9450210947" id="yqtfd80096"><br clear="none"><br clear="none">> Are there any other Write Barrier techniques?</div><br clear="none"><br clear="none">Not sure what the question is: certainly there are other uses of write<br clear="none">barriers than card marking (see above), and different techniques to get<br clear="none">the same effect without using card marks (ie. maintain remembered sets).<br clear="none"><br clear="none">E.g. Xi Yang, Stephen M. Blackburn, Daniel Frampton, and Antony L.<br clear="none">Hosking. 2012. Barriers reconsidered, friendlier still!. SIGPLAN Not.<br clear="none">47, 11 (June 2012), 37-48. DOI=10.1145/2426642.2259004<br clear="none"><a shape="rect" href="http://doi.acm.org/10.1145/2426642.2259004" target="_blank">http://doi.acm.org/10.1145/2426642.2259004 </a>gives an overview of some<br clear="none">kinds of software write barriers, but it maybe also contains a few<br clear="none">useful references for further research.<br clear="none"><br clear="none">Thanks,<br clear="none"> Thomas<div class="yqt9450210947" id="yqtfd54256"><br clear="none"><br clear="none"><br clear="none"></div><br><br></div> </div> </div> </div></div></body></html>