From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45651) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgvMr-0002iT-FN for qemu-devel@nongnu.org; Mon, 05 Sep 2016 10:59:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bgvMn-0000MP-Br for qemu-devel@nongnu.org; Mon, 05 Sep 2016 10:59:24 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48228) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bgvMn-0000MI-5m for qemu-devel@nongnu.org; Mon, 05 Sep 2016 10:59:21 -0400 Date: Mon, 5 Sep 2016 15:59:16 +0100 From: "Daniel P. Berrange" Message-ID: <20160905145916.GI24656@redhat.com> Reply-To: "Daniel P. Berrange" References: <147041636348.2523.2954972609232949598.stgit@fimbulvetr.bsc.es> <20160818105424.GD4850@stefanha-x1.localdomain> <8737lypajh.fsf@fimbulvetr.bsc.es> <20160823155430.GB3948@stefanha-x1.localdomain> <87lgzm4g5p.fsf@fimbulvetr.bsc.es> <20160829134502.GA26282@stefanha-x1.localdomain> <87a8fvjtw5.fsf@fimbulvetr.bsc.es> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87a8fvjtw5.fsf@fimbulvetr.bsc.es> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 0/6] hypertrace: Lightweight guest-to-QEMU trace channel List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , Stefan Hajnoczi , qemu-devel@nongnu.org, Steven Rostedt , Luiz Capitulino , lttng-dev@lists.lttng.org, Masami Hiramatsu On Mon, Aug 29, 2016 at 08:46:02PM +0200, Llu=C3=ADs Vilanova wrote: > Stefan Hajnoczi writes: >=20 > > When SystemTap is used the QEMU monitor interface does nothing. >=20 > That's not what I've experienced. I was able to use a stap script to ch= ange the > tracing state of events: >=20 > #!/usr/bin/env stap >=20 > %{ > #include > %} >=20 > function event:long(cpu:long, addr:long, info:long) > %{ > char *argv[4] =3D {"/bin/sh", "-c", "echo 'trace-event * off' | = telnet localhost 1234", NULL}; > call_usermodehelper(argv[0], argv, NULL, UMH_WAIT_EXEC); > STAP_RETURN(0); > %} I don't know what you're trying to achieve here. The trace-event state, as changed/viewed via QEMU monitor, is irrelevant to the dtrace (systemta= p) backend. dtrace and ltt-ust are both fully dynamic trace event backends, so the QEMU event state has no effect on them. The probe points in the binary are dynamically enabled / disabled by the dtrace runtime. ie dtrac= e will automatically enable an event if you write a dtrace script that uses the event. Regards, Daniel --=20 |: http://berrange.com -o- http://www.flickr.com/photos/dberrange= / :| |: http://libvirt.org -o- http://virt-manager.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vn= c :| From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Daniel P. Berrange" Subject: Re: [PATCH 0/6] hypertrace: Lightweight guest-to-QEMU trace channel Date: Mon, 5 Sep 2016 15:59:16 +0100 Message-ID: <20160905145916.GI24656@redhat.com> References: <147041636348.2523.2954972609232949598.stgit@fimbulvetr.bsc.es> <20160818105424.GD4850@stefanha-x1.localdomain> <8737lypajh.fsf@fimbulvetr.bsc.es> <20160823155430.GB3948@stefanha-x1.localdomain> <87lgzm4g5p.fsf@fimbulvetr.bsc.es> <20160829134502.GA26282@stefanha-x1.localdomain> <87a8fvjtw5.fsf@fimbulvetr.bsc.es> Reply-To: "Daniel P. Berrange" Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Return-path: Content-Disposition: inline In-Reply-To: <87a8fvjtw5.fsf@fimbulvetr.bsc.es> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: "Qemu-devel" To: Stefan Hajnoczi , Stefan Hajnoczi , qemu-devel@nongnu.org, Steven Rostedt , Luiz Capitulino , lttng-dev@lists.lttng.org, Masami Hiramatsu List-Id: lttng-dev@lists.lttng.org On Mon, Aug 29, 2016 at 08:46:02PM +0200, Llu=C3=ADs Vilanova wrote: > Stefan Hajnoczi writes: >=20 > > When SystemTap is used the QEMU monitor interface does nothing. >=20 > That's not what I've experienced. I was able to use a stap script to ch= ange the > tracing state of events: >=20 > #!/usr/bin/env stap >=20 > %{ > #include > %} >=20 > function event:long(cpu:long, addr:long, info:long) > %{ > char *argv[4] =3D {"/bin/sh", "-c", "echo 'trace-event * off' | = telnet localhost 1234", NULL}; > call_usermodehelper(argv[0], argv, NULL, UMH_WAIT_EXEC); > STAP_RETURN(0); > %} I don't know what you're trying to achieve here. The trace-event state, as changed/viewed via QEMU monitor, is irrelevant to the dtrace (systemta= p) backend. dtrace and ltt-ust are both fully dynamic trace event backends, so the QEMU event state has no effect on them. The probe points in the binary are dynamically enabled / disabled by the dtrace runtime. ie dtrac= e will automatically enable an event if you write a dtrace script that uses the event. Regards, Daniel --=20 |: http://berrange.com -o- http://www.flickr.com/photos/dberrange= / :| |: http://libvirt.org -o- http://virt-manager.or= g :| |: http://autobuild.org -o- http://search.cpan.org/~danberr= / :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vn= c :|