On Wed, Oct 20, 2010 at 6:31 PM, Daniel P. Berrange <berra...@redhat.com> wrote:
> This introduces a new tracing backend that targets the SystemTAP
> implementation of DTrace userspace tracing. The core functionality
> should be applicable and standard across any DTrace implementation
> on Solaris, OS-X, *BSD, but the Makefile rules will likely need
> some small additional changes to cope with OS specific build
> requirements.
>
> This backend builds a little differently from the other tracing
> backends. Specifically there is no 'trace.c' file, because the
> 'dtrace' command line tool generates a '.o' file directly from
> the dtrace probe definition file. The probe definition is usually
> named with a '.d' extension but QEMU uses '.d' files for its
> external makefile dependancy tracking, so this uses '.dtrace' as
> the extension for the probe definition file.
>
> The 'tracetool' program gains the ability to generate a trace.h
> file for DTrace, and also to generate the trace.d file containing
> the dtrace probe definition, and finally a qemu.stp file which is
> a wrapper around the probe definition providing more convenient
> access from SystemTAP scripts.
>
> eg, instead of
>
> probe process("qemu").mark("qemu_malloc") {
> printf("Malloc %d %p\n", $arg1, $arg2);
> }
>
> The addition of qemu.stp to /usr/share/systemtap/tapset/
> lets users write
>
> probe qemu.qemu_malloc {
> printf("Malloc %d %p\n", size, ptr);
> }
>
> In v2:
>
> - Add check for 'dtrace' command in configure
> - Comply with coding standards in generated code
> - Misc fixes to tracetool
> - Add more generated files to make clean target
> - Mention 'dtrace' backend in configure help
>
> In v3:
>
> - Make sure dtrace check in configure only runs
> when dtrace backend is selected
>
> Still todo in v4:
>
> - Change process("qemu") statement so that it applies
> to all 'qemu-system-XXX' binaries not just 'qemu'
>
> * .gitignore: Ignore trace-dtrace.*
> * Makefile: Extra rules for generating DTrace files
> * Makefile.obj: Don't build trace.o for DTrace, use
> trace-dtrace.o generated by 'dtrace' instead
> * tracetool: Support for generating DTrace/SystemTAP
> data files
>
> Signed-off-by: Daniel P. Berrange <berra...@redhat.com>
> ---
> .gitignore | 3 +
> Makefile | 32 +++++++++++
> Makefile.objs | 4 ++
> configure | 14 +++++-
> tracetool | 169
> +++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 5 files changed, 211 insertions(+), 11 deletions(-)
Tested successfully both for launching QEMU and attaching to a running process.
This looks promising but it's too bad that utrace isn't upstream. On
my Debian testing development machine I need to rebuild the kernel to
make use of userspace probes with SystemTap.
Acked-by: Stefan Hajnoczi <stefa...@linux.vnet.ibm.com>
Stefan
