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* [PATCH v3 00/24] trace: bugfixes, cleanups and optimizations
@ 2026-10-05 12:08 Daniel P. Berrangé
  2026-10-05 12:08 ` [PATCH v3 01/24] osdep: add 'ignore_value(x)' macro Daniel P. Berrangé
                   ` (23 more replies)
  0 siblings, 24 replies; 25+ messages in thread
From: Daniel P. Berrangé @ 2026-10-05 12:08 UTC (permalink / raw)
  To: qemu-devel
  Cc: Paolo Bonzini, Marc-André Lureau,
	Philippe Mathieu-Daudé, Stefan Hajnoczi,
	Daniel P. Berrangé

This series started off with fixing some compile failures seen
with dtrace and ust backends, and got somewhat out of hand as
I looked more deeply at the trace code. So it ended up doing
various bits of code cleanup and memory usage optimizations.

The optimizations aren't huge against each individual binaries.
There are too many scenarios to show the full set, but here
are some binary size examples

The current git master baseline for different enabled
backends  on the x86_64 emulator:

  nop 88546360
  dtrace 90604496
  ftrace 93265944
  log 93799528
  syslog 93962704
  simple 97064528
  ust 162999944
  dtrace,ftrace,log,syslog,simple,ust 174438088

'ust' has insanely high overhead in terms of binary sizes,
inexplicably insane.

'ftrace/log/syslog' are all similar because their overhead
is dominated by the printf() format strings which are
identical in all.

'simple' is a bit worse because of the helper functions we
must generated for each probe

After this series is applied the results for x86_64 are

  nop 88510248
  dtrace 90576160
  ftrace 93156320
  log 93735064
  syslog 93853480
  simple 97050856
  ust 162957256
  dtrace,ftrace,log,syslog,simple,ust 174431128

IOW, for 'dtrace', we save 28k, for 'log' we save 62k

For the aarch64 binary, we see bigger saving in some
cases:

  baseline dtrace 127610144
  baseline log 131050320
     trace dtrace 127459264
     trace log  130998872

IOW, for 'dtrace' we save 150k, for 'log' we only save
50k. No clue why the saving is not so significant for
the 'log' backend but not a big deal.

Changed in v3:

 * Include QEMU log mask check in Rust generated code too
 * Eliminate duplicate state checks in DSTATE macro

Changed in v2:

 * Improve some commit messages
 * Updated tracing.rst docs

Daniel P. Berrangé (24):
  osdep: add 'ignore_value(x)' macro
  trace: use 'ignore_value()' instead of a dummy variable
  trace: fix handling of char** in UST backend
  hw/xen: replace "long unsigned int" with "unsigned long " for dtrace
  trace: block use of "long int" for dtrace
  trace: drop unused trace_event_set_state_dynamic_init()
  trace: remove obsolete references to vcpu property
  trace: drop 'id' from TraceEvent struct when not required
  trace: change "DSTATE" variables from uint16_t to uint8_t
  trace: add testing of 'nop' trace backend
  trace: don't emit TraceEvent structs when 'nop' backend is used
  trace: add test of generation with all backends enabled
  trace: remove redundant headers from simple trace backend code
  trace: include probe name in Rust format strings
  trace: add missing newline in ftrace Rust format string
  trace: eliminate dupe trace_event_get_state_dynamic_by_id() calls
  audio: remove mistaken use of trace_event_get_state()
  hw/ppc: remove mistaken use of trace_event_get_state()
  monitor: remove mistaken use of trace_event_get_state()
  trace: include qemu_loglevel_mask(LOG_TRACE) in guard
  trace: remove "disable" property from trace files
  trace: stop tracking static disabled state
  trace: remove parsing of "disable" event property
  trace: remove 'trace_event_get_state' wrapper

 audio/audio-mixeng-be.c                      |   2 +-
 docs/devel/tracing.rst                       |  24 +----
 hw/display/trace-events                      |   2 +-
 hw/ppc/vof.c                                 |  13 +--
 hw/xen/trace-events                          |   4 +-
 include/qemu/osdep.h                         |   8 ++
 monitor/qmp.c                                |   4 +-
 qapi/trace.json                              |   5 +-
 scripts/tracetool/__init__.py                |  32 ++----
 scripts/tracetool/backend/__init__.py        |   7 +-
 scripts/tracetool/backend/dtrace.py          |   2 -
 scripts/tracetool/backend/ftrace.py          |   8 +-
 scripts/tracetool/backend/log.py             |  22 ++--
 scripts/tracetool/backend/simple.py          |   9 +-
 scripts/tracetool/backend/syslog.py          |   6 +-
 scripts/tracetool/format/c.py                |  74 +++++++-------
 scripts/tracetool/format/d.py                |   3 -
 scripts/tracetool/format/h.py                |  48 ++++-----
 scripts/tracetool/format/log_stap.py         |   3 -
 scripts/tracetool/format/rs.py               |  30 +++---
 scripts/tracetool/format/simpletrace_stap.py |   3 -
 scripts/tracetool/format/stap.py             |   3 -
 scripts/tracetool/format/ust_events_c.py     |   3 -
 scripts/tracetool/format/ust_events_h.py     |   7 +-
 stubs/trace-control.c                        |   6 --
 target/hppa/trace-events                     |  28 +++---
 tests/tracetool/all.c                        |  61 +++++++++++
 tests/tracetool/all.d                        |  10 ++
 tests/tracetool/all.h                        | 100 +++++++++++++++++++
 tests/tracetool/all.log-stap                 |  15 +++
 tests/tracetool/all.rs                       |  98 ++++++++++++++++++
 tests/tracetool/all.simpletrace-stap         |  16 +++
 tests/tracetool/all.stap                     |  14 +++
 tests/tracetool/all.ust-events-c             |  14 +++
 tests/tracetool/all.ust-events-h             |  56 +++++++++++
 tests/tracetool/dtrace.c                     |  10 +-
 tests/tracetool/dtrace.h                     |   6 +-
 tests/tracetool/dtrace.rs                    |   6 +-
 tests/tracetool/ftrace.c                     |  10 +-
 tests/tracetool/ftrace.h                     |  14 ++-
 tests/tracetool/ftrace.rs                    |  10 +-
 tests/tracetool/log.c                        |  10 +-
 tests/tracetool/log.h                        |  26 +++--
 tests/tracetool/log.rs                       |  12 ++-
 tests/tracetool/meson.build                  |   4 +-
 tests/tracetool/nop.c                        |   7 ++
 tests/tracetool/nop.h                        |  25 +++++
 tests/tracetool/nop.rs                       |  51 ++++++++++
 tests/tracetool/simple.c                     |  12 +--
 tests/tracetool/simple.h                     |  10 +-
 tests/tracetool/simple.rs                    |   6 +-
 tests/tracetool/syslog.c                     |  10 +-
 tests/tracetool/syslog.h                     |  14 ++-
 tests/tracetool/syslog.rs                    |  10 +-
 tests/tracetool/tracetool-test.py            |  12 ++-
 tests/tracetool/ust.c                        |  10 +-
 tests/tracetool/ust.h                        |   6 +-
 trace/control-internal.h                     |   8 +-
 trace/control-target.c                       |  29 ------
 trace/control.c                              |  19 +---
 trace/control.h                              |  43 +-------
 trace/event-internal.h                       |  19 +---
 trace/ftrace.c                               |   3 +-
 trace/qmp.c                                  |  47 +++------
 trace/simple.c                               |   9 +-
 65 files changed, 749 insertions(+), 449 deletions(-)
 create mode 100644 tests/tracetool/all.c
 create mode 100644 tests/tracetool/all.d
 create mode 100644 tests/tracetool/all.h
 create mode 100644 tests/tracetool/all.log-stap
 create mode 100644 tests/tracetool/all.rs
 create mode 100644 tests/tracetool/all.simpletrace-stap
 create mode 100644 tests/tracetool/all.stap
 create mode 100644 tests/tracetool/all.ust-events-c
 create mode 100644 tests/tracetool/all.ust-events-h
 create mode 100644 tests/tracetool/nop.c
 create mode 100644 tests/tracetool/nop.h
 create mode 100644 tests/tracetool/nop.rs

-- 
2.55.0



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Thread overview: 25+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-10-05 12:08 [PATCH v3 00/24] trace: bugfixes, cleanups and optimizations Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 01/24] osdep: add 'ignore_value(x)' macro Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 02/24] trace: use 'ignore_value()' instead of a dummy variable Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 03/24] trace: fix handling of char** in UST backend Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 04/24] hw/xen: replace "long unsigned int" with "unsigned long " for dtrace Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 05/24] trace: block use of "long int" " Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 06/24] trace: drop unused trace_event_set_state_dynamic_init() Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 07/24] trace: remove obsolete references to vcpu property Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 08/24] trace: drop 'id' from TraceEvent struct when not required Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 09/24] trace: change "DSTATE" variables from uint16_t to uint8_t Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 10/24] trace: add testing of 'nop' trace backend Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 11/24] trace: don't emit TraceEvent structs when 'nop' backend is used Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 12/24] trace: add test of generation with all backends enabled Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 13/24] trace: remove redundant headers from simple trace backend code Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 14/24] trace: include probe name in Rust format strings Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 15/24] trace: add missing newline in ftrace Rust format string Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 16/24] trace: eliminate dupe trace_event_get_state_dynamic_by_id() calls Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 17/24] audio: remove mistaken use of trace_event_get_state() Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 18/24] hw/ppc: " Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 19/24] monitor: " Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 20/24] trace: include qemu_loglevel_mask(LOG_TRACE) in guard Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 21/24] trace: remove "disable" property from trace files Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 22/24] trace: stop tracking static disabled state Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 23/24] trace: remove parsing of "disable" event property Daniel P. Berrangé
2026-10-05 12:08 ` [PATCH v3 24/24] trace: remove 'trace_event_get_state' wrapper Daniel P. Berrangé

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