From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefan Hajnoczi Subject: Re: [Qemu-devel] [PATCH 0/6] hypertrace: Lightweight guest-to-QEMU trace channel Date: Thu, 18 Aug 2016 14:53:27 +0100 Message-ID: <20160818135327.GJ4850__23321.8245128684$1471528423$gmane$org@stefanha-x1.localdomain> References: <147041636348.2523.2954972609232949598.stgit@fimbulvetr.bsc.es> <20160818094720.GA4850@stefanha-x1.localdomain> <87wpjeqsv9.fsf@fimbulvetr.bsc.es> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0355525449713057246==" Return-path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by evm-lttng-1.efficios.com (Postfix) with ESMTPS id 3F207A2A23 for ; Thu, 18 Aug 2016 13:53:36 +0000 (UTC) In-Reply-To: <87wpjeqsv9.fsf@fimbulvetr.bsc.es> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" To: Stefan Hajnoczi , qemu-devel@nongnu.org, Steven Rostedt , Luiz Capitulino , lttng-dev@lists.lttng.org, Masami Hiramatsu List-Id: lttng-dev@lists.lttng.org --===============0355525449713057246== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="mPTHnM80CEnHQ2WJ" Content-Disposition: inline --mPTHnM80CEnHQ2WJ Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Aug 18, 2016 at 12:22:18PM +0200, Llu=EDs Vilanova wrote: > Stefan Hajnoczi writes: >=20 > > On Fri, Aug 05, 2016 at 06:59:23PM +0200, Llu=EDs Vilanova wrote: > >> The hypertrace channel allows guest code to emit events in QEMU (the h= ost) using > >> its tracing infrastructure (see "docs/trace.txt"). This works in both = 'system' > >> and 'user' modes. That is, hypertrace is to tracing, what hypercalls a= re to > >> system calls. > >>=20 > >> You can use this to emit an event on both guest and QEMU (host) traces= to easily > >> synchronize or correlate them. You could also modify you guest's traci= ng system > >> to emit all events through the hypertrace channel, providing a unified= and fully > >> synchronized trace log. Another use case is timing the performance of = guest code > >> when optimizing TCG (QEMU traces have a timestamp). > >>=20 > >> See first commit for a full description. > >>=20 > >> Signed-off-by: Llu=EDs Vilanova > >> --- >=20 > > CCing Steven Rostedt, Masami Hiramatsu, Luiz Capitulino, and LTTng folks > > who have all looked into host/guest tracing solutions. > [...] >=20 > Oh, I wasn't aware of that. I'm certainly interested in collaborating. They are working on or have worked on different approaches to host/guest tracing. Unfortunately there isn't an out-of-the-box solution as far as I know. It would be nice if there was a documented host/guest tracing approach that didn't involve much manual setup and handled most use cases. Stefan --mPTHnM80CEnHQ2WJ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJXtb3XAAoJEJykq7OBq3PIwsoH/2UNq012uaauQNC4XY1dskPf 6+9xwwq3xhmb3UzXtVX4Fe1ZM7YXpa5OoqEZJeNdShJHc957F3s77AbpU9cJUG6D Oh37a2TwOSRj/uRetid0Y51gGeSyc5/wFdIkhDaIAVKk2UgGN50i0NUMbIa1Ggaj Kuo99BGB4L08XWgnz9YSKM3O3FeGlP/PIphi9OcTLocPE7d6Gw3Ox0FAkTQT+q/Y qqxRE60U6XLeDVCkrbDkRPpRAwsGzP8vhep7OflBQzHcRPBje1RYnFmuDi/5KpC4 LBacb8/wM9N8rOb597f9D/SCvua6uqG0Lqrpnb864Lz3zXuhnSuLo0xovPUYPso= =VVba -----END PGP SIGNATURE----- --mPTHnM80CEnHQ2WJ-- --===============0355525449713057246== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KbHR0bmctZGV2 IG1haWxpbmcgbGlzdApsdHRuZy1kZXZAbGlzdHMubHR0bmcub3JnCmh0dHBzOi8vbGlzdHMubHR0 bmcub3JnL2NnaS1iaW4vbWFpbG1hbi9saXN0aW5mby9sdHRuZy1kZXYK --===============0355525449713057246==--