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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()
53 lines
1.5 KiB
Python
53 lines
1.5 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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"""
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Ftrace built-in backend.
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"""
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__author__ = "Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>"
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__copyright__ = "Copyright (C) 2013 Hitachi, Ltd."
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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@redhat.com"
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from tracetool import out
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PUBLIC = True
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def generate_h_begin(events, group):
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out('#include "trace/ftrace.h"',
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'')
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def generate_h(event, group):
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argnames = ", ".join(event.args.names())
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if len(event.args) > 0:
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argnames = ", " + argnames
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out(' {',
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' char ftrace_buf[MAX_TRACE_STRLEN];',
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' int unused __attribute__ ((unused));',
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' int trlen;',
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' if (trace_event_get_state(%(event_id)s)) {',
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' trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
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' "%(name)s " %(fmt)s "\\n" %(argnames)s);',
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' trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
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' unused = write(trace_marker_fd, ftrace_buf, trlen);',
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' }',
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' }',
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name=event.name,
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args=event.args,
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event_id="TRACE_" + event.name.upper(),
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fmt=event.fmt.rstrip("\n"),
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argnames=argnames)
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def generate_h_backend_dstate(event, group):
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out(' trace_event_get_state_dynamic_by_id(%(event_id)s) || \\',
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event_id="TRACE_" + event.name.upper())
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