From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58059) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S7434-0001Db-Sw for qemu-devel@nongnu.org; Mon, 12 Mar 2012 08:08:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S742y-0006Cc-Jb for qemu-devel@nongnu.org; Mon, 12 Mar 2012 08:08:22 -0400 Received: from mx1.redhat.com ([209.132.183.28]:4431) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S742y-0006CQ-Bf for qemu-devel@nongnu.org; Mon, 12 Mar 2012 08:08:16 -0400 Message-ID: <4F5DE72A.1000103@redhat.com> Date: Mon, 12 Mar 2012 14:08:10 +0200 From: Avi Kivity MIME-Version: 1.0 References: <1331302420-29737-1-git-send-email-stefanha@linux.vnet.ibm.com> In-Reply-To: <1331302420-29737-1-git-send-email-stefanha@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] kvm: add flightrecorder script List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Anthony Liguori , qemu-devel@nongnu.org, kvm@vger.kernel.org On 03/09/2012 04:13 PM, Stefan Hajnoczi wrote: > The kvm kernel module includes a number of trace events which can be > useful when debugging system behavior. Even on production systems these > trace events can be used to observe guest behavior and identify the > source of problems. > > The kvm_flightrecorder script is a command-line wrapper for the > /sys/kernel/debug/tracing interface. Kernel symbols do not need to be > installed. > > This script captures a fixed-size buffer of KVM trace events. Recent > events overwrite the oldest events when the buffer size is exceeded and > it is possible to leave KVM tracing enabled for any period of time with > just a fixed-size buffer. If the buffer is large enough this script is > a useful tool for collecting detailed information after an issue occurs > with a guest. Hence the name "flight recorder". > > The script can also be used in 'tail' mode to simply view KVM trace > events as they occur. This is handy for development and to ensure that > the guest is indeed running. > > Have you considered updating trace-cmd or perf-something instead? While each of these tools are useful we miss out on combining capabilities. For example you could 'perf probe' a dynamic tracepoint and flightrecord it together with kvm tracepoints. -- error compiling committee.c: too many arguments to function