From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26879 invoked by alias); 8 Aug 2012 21:11:51 -0000 Received: (qmail 26866 invoked by uid 22791); 8 Aug 2012 21:11:49 -0000 X-SWARE-Spam-Status: No, hits=-8.8 required=5.0 tests=AWL,BAYES_00,KHOP_PGP_SIGNED,KHOP_RCVD_UNTRUST,MAY_BE_FORGED,RCVD_IN_DNSWL_HI,RCVD_IN_HOSTKARMA_W,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 08 Aug 2012 21:11:30 +0000 Received: from int-mx12.intmail.prod.int.phx2.redhat.com (int-mx12.intmail.prod.int.phx2.redhat.com [10.5.11.25]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q78LBTOY023153 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 8 Aug 2012 17:11:29 -0400 Received: from redhat.com (unused [10.15.16.143] (may be forged)) by int-mx12.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id q78LBNkq027597 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Wed, 8 Aug 2012 17:11:28 -0400 Date: Wed, 08 Aug 2012 21:11:00 -0000 From: Lukas Berk To: Jon VanAlten Cc: systemtap@sourceware.org, distro-pkg-dev@openjdk.java.net Subject: Re: [RFC] Enhanced Garbage Collection Probe Points Message-ID: <20120808211122.GA17399@redhat.com> Reply-To: Lukas Berk References: <20120802131039.GA1955@redhat.com> <1956303607.34675944.1344458257034.JavaMail.root@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="IS0zKkzwUGydFO0o" Content-Disposition: inline In-Reply-To: <1956303607.34675944.1344458257034.JavaMail.root@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-IsSubscribed: yes Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org X-SW-Source: 2012-q3/txt/msg00179.txt.bz2 --IS0zKkzwUGydFO0o Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Content-length: 2419 * Jon VanAlten [2012-08-08 16:38]: [...] >=20 > Hi Lukas, >=20 > I've had a look at the patch, and the rest of the thread (especially the > tapset you posted, which made things a LOT more clear so thanks for that). > I hope that you'll continue to refine the tapset and contribute that as > well so that us java hackers who are brave enough to play with Systemtap > have the nice friendly probe names and variables to work with! Thanks for taking a look, I'll make sure to include it in future revisions, ideally I'll have a gc_details.stp.in file that will have the .so path change based on the system it's being compiled for. (similar to the hotspot{,_jni}.stp.in and jstack.stp.in files already included) >=20 > The patch itself seems fine, although I'll just have to trust you that the > probes are in the right place as I'm not really a hotspot hacker myself. > Really I would hope that someone who is more familiar with the GC code > base will comment from that perspective. >=20 > I assume that none of these probes require any special VM args to functio= n? > A related question, and this might be hard to answer being rather open > ended, but are you aware of any VM args that would affect/interfere with > the functioning of these probes? The only arguments that I can think of that will immediately effect these probes are: -XX:+UseSerialGC -XX:+UseParallelGC -XX:+UseParallelOldGC -XX:+UseParNewGC -XX:+UseConcMarkSweepGc -XX:+UseG1GC which will force the JVM to use the designated type of garbage collection. There may be more I'm missing (please let me know if there are). >=20 > There is a begin and and end probe for some types of collection and even > phases within collection, so it seems odd to me that for G1 stop-the-world > collection there is not. Am I missing something? My thought in adding the begin/end probes was to be able to track parallel operations and tie a specific pid to an collection/scavenge to an object. That wouldn't be needed in serial operation. However, now that I think about it, it could be useful to mark the beginning and end of 'serial' collections from a timing perspective, and its trivial to add (I'll include it in a revised patch). >=20 > Other than that; great start, this definitely has stuff interesting from a > Thermostat perspective and the potential for more :D >=20 Thanks for the comments, Lukas [1] - http://dacapobench.org/ --IS0zKkzwUGydFO0o Content-Type: application/pgp-signature Content-length: 836 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJQItX6AAoJEAaRCclx+kwJugAQAKV/zN8nHlxC6090l5xGyU4K f3tIUuV68Ry8Q1HAE+Rek1qisEpSHzpWhqiYX9FZk2me5mJDBkqrPfJDctXpJHD3 Wzwt+Fvh3OtVtXuWnDVdIqtNStPe/Ud95KWB/LZU13DP+AJ2cVnVRwN7nXVEqP08 1ddvBCrtQn/UHGKhtLd0aKRYuCu8QVyJWRj2qpxZ866UqV67eSJ7W62k3XVIq5rP REdliSLcE8ONuWULpbO23+5RxQbwIbf7YXShC6YK+u9/4/unhCj3FumMv0TxBrM7 ulHmq0jXqsEe2URrFIlOcTnV+ydO1/ZHyhs6lAV1KCQxP3WjHLwEVe7Q6J66OSE4 lEb4XahLd+xsNLb3iyZxuaz5MdEDSMHwuPtgiz3z1vUpdLU9TUsUcnhDc/PPTKFi bIjB9kDdaA9fZiw7s96wQrz7AX7Qu26/M060FRyuhk1fmxLPpG5/f5fcL5sXzV/9 iElXy2juzD3JiWwECTlZRdLMM4Ll1GkHNBvS3MZ8gpWxd6nuGliYgDQgFmwK/wqf NuoLDWuXQ/PgDgBUAU1HkSAESDSWmOKCvKf/GQGECgzr21qApIBl6rReXDTJ8W23 U8CFgSIEgqE6OaGQI/XvtjrBIuSv6Xz+TGM4em+y0pduld1O8FekLZgadoO0Tx6K A2jzNLsWq8wWG25RK344 =P6WS -----END PGP SIGNATURE----- --IS0zKkzwUGydFO0o--