From 3932ef3ffb54baf22ab05767e827bda1834d20df Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 31 Jul 2017 15:07:17 +0100 Subject: trace: add TRACE__BACKEND_DSTATE() QEMU keeps track of trace event enabled/disabled state and provides monitor commands to inspect and modify the "dstate". SystemTap and LTTng UST maintain independent enabled/disabled states for each trace event, the other backends rely on QEMU dstate. Introduce a new per-event macro that combines backend-specific dstate like this: #define TRACE_MY_EVENT_BACKEND_DSTATE() ( \ QEMU_MY_EVENT_ENABLED() || /* SystemTap */ \ tracepoint_enabled(qemu, my_event) /* LTTng UST */ || \ false) This will be used to extend trace_event_get_state() in the next patch. [Daniel Berrange pointed out that QEMU_MY_EVENT_ENABLED() must be true by default, not false. This way events will fire even if the DTrace implementation does not implement the SystemTap semaphores feature. Ubuntu Precise uses lttng-ust-dev 2.0.2 which does not have tracepoint_enabled(), so we need a compatibility wrapper to keep Travis builds passing. --Stefan] Signed-off-by: Stefan Hajnoczi Message-id: 20170731140718.22010-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi fixup! trace: add TRACE__BACKEND_DSTATE() --- scripts/tracetool/backend/ust.py | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'scripts/tracetool/backend/ust.py') diff --git a/scripts/tracetool/backend/ust.py b/scripts/tracetool/backend/ust.py index 2adaf548d5..280cb7c106 100644 --- a/scripts/tracetool/backend/ust.py +++ b/scripts/tracetool/backend/ust.py @@ -27,6 +27,11 @@ def generate_h_begin(events, group): out('#include ', '#include "%s"' % header, + '', + '/* tracepoint_enabled() was introduced in LTTng UST 2.7 */', + '#ifndef tracepoint_enabled', + '#define tracepoint_enabled(a, b) true', + '#endif', '') @@ -38,3 +43,8 @@ def generate_h(event, group): out(' tracepoint(qemu, %(name)s%(tp_args)s);', name=event.name, tp_args=argnames) + + +def generate_h_backend_dstate(event, group): + out(' tracepoint_enabled(qemu, %(name)s) || \\', + name=event.name) -- cgit v1.2.3-55-g7522