--- /dev/null +++ b/README.systemtap @@ -0,0 +1,43 @@ +QEMU tracing using systemtap-initscript +--------------------------------------- + +You can capture QEMU trace data all the time using systemtap-initscript. This +uses SystemTap's flight recorder mode to trace all running guests to a +fixed-size buffer on the host. Old trace entries are overwritten by new +entries when the buffer size wraps. + +1. Install the systemtap-initscript package: + # yum install systemtap-initscript + +2. Install the systemtap scripts and the conf file: + # cp /usr/share/qemu-kvm/systemtap/script.d/qemu_kvm.stp /etc/systemtap/script.d/ + # cp /usr/share/qemu-kvm/systemtap/conf.d/qemu_kvm.conf /etc/systemtap/conf.d/ + +The set of trace events to enable is given in qemu_kvm.stp. This SystemTap +script can be customized to add or remove trace events provided in +/usr/share/systemtap/tapset/qemu-kvm-simpletrace.stp. + +SystemTap customizations can be made to qemu_kvm.conf to control the flight +recorder buffer size and whether to store traces in memory only or disk too. +See stap(1) for option documentation. + +3. Start the systemtap service. + # service systemtap start qemu_kvm + +4. Make the service start at boot time. + # chkconfig systemtap on + +5. Confirm that the service works. + # service systemtap status qemu_kvm + qemu_kvm is running... + +When you want to inspect the trace buffer, perform the following steps: + +1. Dump the trace buffer. + # staprun -A qemu_kvm >/tmp/trace.log + +2. Start the systemtap service because the preceding step stops the service. + # service systemtap start qemu_kvm + +3. Translate the trace record to readable format. + # /usr/share/qemu-kvm/simpletrace.py --no-header /usr/share/qemu-kvm/trace-events /tmp/trace.log