3932ef3ffb
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 <stefanha@redhat.com>
Message-id: 20170731140718.22010-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
fixup! trace: add TRACE_<event>_BACKEND_DSTATE()
51 lines
1.2 KiB
Python
51 lines
1.2 KiB
Python
#!/usr/bin/env python
|
|
# -*- coding: utf-8 -*-
|
|
|
|
"""
|
|
LTTng User Space Tracing backend.
|
|
"""
|
|
|
|
__author__ = "Lluís Vilanova <vilanova@ac.upc.edu>"
|
|
__copyright__ = "Copyright 2012-2017, Lluís Vilanova <vilanova@ac.upc.edu>"
|
|
__license__ = "GPL version 2 or (at your option) any later version"
|
|
|
|
__maintainer__ = "Stefan Hajnoczi"
|
|
__email__ = "stefanha@linux.vnet.ibm.com"
|
|
|
|
|
|
from tracetool import out
|
|
|
|
|
|
PUBLIC = True
|
|
|
|
|
|
def generate_h_begin(events, group):
|
|
if group == "root":
|
|
header = "trace-ust-root.h"
|
|
else:
|
|
header = "trace-ust.h"
|
|
|
|
out('#include <lttng/tracepoint.h>',
|
|
'#include "%s"' % header,
|
|
'',
|
|
'/* tracepoint_enabled() was introduced in LTTng UST 2.7 */',
|
|
'#ifndef tracepoint_enabled',
|
|
'#define tracepoint_enabled(a, b) true',
|
|
'#endif',
|
|
'')
|
|
|
|
|
|
def generate_h(event, group):
|
|
argnames = ", ".join(event.args.names())
|
|
if len(event.args) > 0:
|
|
argnames = ", " + argnames
|
|
|
|
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)
|