This is a short HOWTO for using KVM TRACE.
1) Enable Kernel
================
Enable CONFIG_KVM_TRACE in your kernel config. You will enable
CONFIG_MARKERS & CONFIG_SYSFS to enable. CONFIG_DEBUG_FS should be
enabled once you enable KVM_TRACE.
Build and boot.
2) Mount debugfs
================
You must mount debugfs before using kvmtrace. One way to do this is
by placing an entry into your /etc/fstab , such as the following:
debugfs /sys/kernel/debug debugfs defaults 0 0
Reboot and it will mounted.
3) Build kvmtrace tool
======================
Go to kvm-userspace directory. Configure the directory with the
configure command. Then go to "kvm-userspace/user" directory and type
command: "make kvmtrace".
This will build the trace tool you'll need to generate your trace file.
Copy tool over to machine, so you can execute it later.
4) Running kvmtrace
=====================
Once on kvm host start a guest. To trace KVM use the kvmtrace tool, like
in the following example.
./kvmtrace -o TRACE1 -w 5
This will run kvmtrace tool for 5 seconds and produce a binary file with
your trace output named "TRACE1.kvmtrace.0".
5) Reading the data
======================
Copy file with trace output to somewhere you can access. Go back into
kvm-userspace/user directory. You will need two files:
-kvmtrace_format
-formats <-- file describes how to printout the kvmtrace events into a
readable form
Make sure your system has python. Now run kvmtrace_format like the
following:
cat TRACE1.kvmtrace.0 | ./kvmtrace_format formats
You will then see your trace points displayed in a readable form.
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