From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH 1/2] trace: Add simple tracing support Date: Fri, 21 May 2010 13:13:49 +0200 Message-ID: <4BF66AED.5080201@siemens.com> References: <1274434947-2863-1-git-send-email-stefanha@linux.vnet.ibm.com> <1274434947-2863-2-git-send-email-stefanha@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Prerna Saxena , Anthony Liguori To: Stefan Hajnoczi Return-path: Received: from david.siemens.de ([192.35.17.14]:19651 "EHLO david.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753662Ab0EULOA (ORCPT ); Fri, 21 May 2010 07:14:00 -0400 In-Reply-To: <1274434947-2863-2-git-send-email-stefanha@linux.vnet.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: Stefan Hajnoczi wrote: > Trace events should be defined in trace.h. Events are written to > /tmp/trace.log and can be formatted using trace.py. Remember to add > events to trace.py for pretty-printing. When already writing to a file, why not reusing QEMU's logging infrastructure ("log " / "-d foo")? Shouldn't make a huge performance difference if the data is saved in clear-text. Also, having support for ftrace's user space markers would be a very nice option (only an option as it's Linux-specific), see http://lwn.net/Articles/366796. This allows to correlate kernel events (KVM as well as others) with what goes on in QEMU. It simply enables integration with the whole kernel tracing infrastructure, e.g. KernelShark (http://people.redhat.com/srostedt/kernelshark/HTML). Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux