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()
64 lines
1.4 KiB
Python
64 lines
1.4 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""
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DTrace/SystemTAP backend.
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"""
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__author__ = "Lluís Vilanova <vilanova@ac.upc.edu>"
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__copyright__ = "Copyright 2012-2017, Lluís Vilanova <vilanova@ac.upc.edu>"
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__license__ = "GPL version 2 or (at your option) any later version"
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__maintainer__ = "Stefan Hajnoczi"
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__email__ = "stefanha@linux.vnet.ibm.com"
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from tracetool import out
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PUBLIC = True
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PROBEPREFIX = None
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def probeprefix():
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if PROBEPREFIX is None:
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raise ValueError("you must set PROBEPREFIX")
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return PROBEPREFIX
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BINARY = None
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def binary():
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if BINARY is None:
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raise ValueError("you must set BINARY")
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return BINARY
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def generate_h_begin(events, group):
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if group == "root":
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header = "trace-dtrace-root.h"
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else:
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header = "trace-dtrace.h"
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out('#include "%s"' % header,
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'')
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# SystemTap defines <provider>_<name>_ENABLED() but other DTrace
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# implementations might not.
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for e in events:
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out('#ifndef QEMU_%(uppername)s_ENABLED',
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'#define QEMU_%(uppername)s_ENABLED() true',
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'#endif',
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uppername=e.name.upper())
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def generate_h(event, group):
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out(' QEMU_%(uppername)s(%(argnames)s);',
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uppername=event.name.upper(),
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argnames=", ".join(event.args.names()))
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def generate_h_backend_dstate(event, group):
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out(' QEMU_%(uppername)s_ENABLED() || \\',
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uppername=event.name.upper())
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