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trace: [tcg] Do not generate TCG code to trace dynamically-disabled events

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If an event is dynamically disabled, the TCG code that calls the
execution-time tracer is not generated.

Removes the overheads of execution-time tracers for dynamically disabled
events. As a bonus, also avoids checking the event state when the
execution-time tracer is called from TCG-generated code (since otherwise
TCG would simply not call it).

Signed-off-by: Lluís Vilanova <vilanova@ac.upc.edu>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 149915799921.6295.13067154430923434035.stgit@frigg.lan
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Lluís Vilanova 2017-07-04 10:46:39 +02:00 • committed by Stefan Hajnoczi
parent 61a67f71dd
commit 864a2178d4
4 changed files with 41 additions and 14 deletions
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26
scripts/tracetool/format/h.py
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@ -6,7 +6,7 @@ trace/generated-tracers.h
"""
__author__ = "Lluís Vilanova <vilanova@ac.upc.edu>"
__copyright__ = "Copyright 2012-2016, 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"
@ -49,6 +49,19 @@ def generate(events, backend, group):
backend.generate_begin(events, group)
for e in events:
# tracer without checks
out('',
'static inline void %(api)s(%(args)s)',
'{',
api=e.api(e.QEMU_TRACE_NOCHECK),
args=e.args)
if "disable" not in e.properties:
backend.generate(e, group)
out('}')
# tracer wrapper with checks (per-vCPU tracing)
if "vcpu" in e.properties:
trace_cpu = next(iter(e.args))[1]
cond = "trace_event_get_vcpu_state(%(cpu)s,"\
@ -63,16 +76,15 @@ def generate(events, backend, group):
'static inline void %(api)s(%(args)s)',
'{',
' if (%(cond)s) {',
' %(api_nocheck)s(%(names)s);',
' }',
'}',
api=e.api(),
api_nocheck=e.api(e.QEMU_TRACE_NOCHECK),
args=e.args,
names=", ".join(e.args.names()),
cond=cond)
if "disable" not in e.properties:
backend.generate(e, group)
out(' }',
'}')
backend.generate_end(events, group)
out('#endif /* TRACE_%s_GENERATED_TRACERS_H */' % group.upper())