[PATCH RFC 00/21] perf intel-pt: Better support for perf record --cpu

Adrian Hunter
2022-04-22T16:24:38Z

Hi

Here are patches to support capturing Intel PT sideband events such as
mmap, task, context switch, text poke etc, on every CPU even when tracing
selected user_requested_cpus. That is, when using the perf record -C or
--cpu option.

This is needed for:
1. text poke: a text poke on any CPU affects all CPUs
2. tracing user space: a user space process can migrate between CPUs so
mmap events that happen on a different CPU can be needed to decode a
user_requested_cpus CPU.

For example:

Trace on CPU 1:

perf record --kcore -C 1 -e intel_pt// &

Start a task on CPU 0:

taskset 0x1 testprog &

Migrate it to CPU 1:

taskset -p 0x2 <testprog pid>

Stop tracing:

kill %1

Prior to these changes there will be errors decoding testprog
in userspace because the comm and mmap events for testprog will not
have been captured.

There is quite a bit of preparation:

The first 5 patches stop auxtrace mixing up mmap idx between evlist and
evsel. That is going to matter when
evlist->all_cpus != evlist->user_requested_cpus != evsel->cpus:

libperf evsel: Factor out perf_evsel__ioctl()
libperf evsel: Add perf_evsel__enable_thread()
perf evlist: Use libperf functions in evlist__enable_event_idx()
perf auxtrace: Move evlist__enable_event_idx() to auxtrace.c
perf auxtrace: Do not mix up mmap idx

The next 6 patches stop attempts to auxtrace mmap when it is not an
auxtrace event e.g. when mmapping the CPUs on which only sideband is
captured:

libperf evlist: Remove ->idx() per_cpu parameter
libperf evlist: Move ->idx() into mmap_per_evsel()
libperf evlist: Add evsel as a parameter to ->idx()
perf auxtrace: Record whether an auxtrace mmap is needed
perf auxctrace: Add mmap_needed to auxtrace_mmap_params
perf auxtrace: Remove auxtrace_mmap_params__set_idx() per_cpu parameter

The next 5 patches switch to setting up dummy event maps before adding the
evsel so that the evsel is subject to map propagation, primarily to cause
addition of the evsel's CPUs to all_cpus.

perf evlist: Factor out evlist__dummy_event()
perf evlist: Add evlist__add_system_wide_dummy()
perf record: Use evlist__add_system_wide_dummy() in record__config_text_poke()
perf intel-pt: Use evlist__add_system_wide_dummy() for switch tracking
perf intel-pt: Track sideband system-wide when needed

The remaining 5 patches make more significant changes.

First change from using user_requested_cpus to using all_cpus where necessary:

perf tools: Allow all_cpus to be a superset of user_requested_cpus

Secondly, mmap all per-thread and all per-cpu events:

libperf evlist: Allow mixing per-thread and per-cpu mmaps

Stop using system_wide flag for uncore because it will not work anymore:

perf stat: Add per_cpu_only flag for uncore

Finally change map propagation so that system-wide events retain their cpus and
(dummy) threads:

perf tools: Allow system-wide events to keep their own CPUs
perf tools: Allow system-wide events to keep their own threads

Adrian Hunter (21):
libperf evsel: Factor out perf_evsel__ioctl()
libperf evsel: Add perf_evsel__enable_thread()
perf evlist: Use libperf functions in evlist__enable_event_idx()
perf auxtrace: Move evlist__enable_event_idx() to auxtrace.c
perf auxtrace: Do not mix up mmap idx
libperf evlist: Remove ->idx() per_cpu parameter
libperf evlist: Move ->idx() into mmap_per_evsel()
libperf evlist: Add evsel as a parameter to ->idx()
perf auxtrace: Record whether an auxtrace mmap is needed
perf auxctrace: Add mmap_needed to auxtrace_mmap_params
perf auxtrace: Remove auxtrace_mmap_params__set_idx() per_cpu parameter
perf evlist: Factor out evlist__dummy_event()
perf evlist: Add evlist__add_system_wide_dummy()
perf record: Use evlist__add_system_wide_dummy() in record__config_text_poke()
perf intel-pt: Use evlist__add_system_wide_dummy() for switch tracking
perf intel-pt: Track sideband system-wide when needed
perf tools: Allow all_cpus to be a superset of user_requested_cpus
libperf evlist: Allow mixing per-thread and per-cpu mmaps
perf stat: Add per_cpu_only flag for uncore
perf tools: Allow system-wide events to keep their own CPUs
perf tools: Allow system-wide events to keep their own threads

tools/lib/perf/evlist.c | 67 +++++++------------
tools/lib/perf/evsel.c | 29 +++++++--
tools/lib/perf/include/internal/evlist.h | 3 +-
tools/lib/perf/include/internal/evsel.h | 1 +
tools/lib/perf/include/perf/evsel.h | 1 +
tools/perf/arch/arm/util/cs-etm.c | 1 +
tools/perf/arch/arm64/util/arm-spe.c | 1 +
tools/perf/arch/s390/util/auxtrace.c | 1 +
tools/perf/arch/x86/util/intel-bts.c | 1 +
tools/perf/arch/x86/util/intel-pt.c | 32 ++++------
tools/perf/builtin-record.c | 39 +++++-------
tools/perf/builtin-stat.c | 5 +-
tools/perf/util/auxtrace.c | 31 +++++++--
tools/perf/util/auxtrace.h | 8 ++-
tools/perf/util/evlist.c | 106 +++++++++++++++----------------
tools/perf/util/evlist.h | 7 +-
tools/perf/util/evsel.c | 1 +
tools/perf/util/evsel.h | 1 +
tools/perf/util/mmap.c | 4 +-
tools/perf/util/parse-events.c | 2 +-
20 files changed, 176 insertions(+), 165 deletions(-)

Regards
Adrian