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Date: Wed, 25 May 2022 08:00:45 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Adrian Hunter <adrian.hunter@...el.com>,
Jiri Olsa <jolsa@...hat.com>,
Alexey Bayduraev <alexey.v.bayduraev@...ux.intel.com>,
Namhyung Kim <namhyung@...nel.org>,
Leo Yan <leo.yan@...aro.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V4 00/15] perf intel-pt: Better support for perf record
--cpu
Em Tue, May 24, 2022 at 10:01:01PM -0700, Ian Rogers escreveu:
> On Tue, May 24, 2022 at 12:55 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
> >
> > Hi
> >
> > Here are V4 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 patch is a small Intel PT test for system-wide side band. The
> > test fails before the patches are applied, passed afterwards.
> >
> > perf intel-pt: Add a test for system-wide side band [new in V1]
> >
> > The next 5 patches (now already applied) 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() [now applied]
> > 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 (first 4 now already applied) 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 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
> > libperf evlist: Check nr_mmaps is correct [new in V1]
> >
> > Stop using system_wide flag for uncore because it will not work anymore:
> >
> > perf stat: Add requires_cpu flag for uncore
> > libperf evsel: Add comments for booleans [new in V1]
> >
> > 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
> >
> >
> > Changes in V4:
> >
> > Added Acked-by: Namhyung Kim <namhyung@...nel.org>
> > Added a couple Acked-by: Ian Rogers <irogers@...gle.com>
>
> Would love to see this merged Arnaldo, I can do an:
>
> Acked-by: Ian Rogers <irogers@...gle.com>
>
> in case it helps you with b4 a little :-)
I'll add your Acked-by manually now to the patches missing it, as I had merged this yesterday.
- Arnaldo
> Thanks,
> Ian
>
> > perf intel-pt: Add a test for system-wide side band
> > Put in commit message that test succeeds only after other
> > patches applied
> >
> > 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
> > Omitted because already applied
> >
> > libperf evsel: Add comments for booleans
> > Amended comment about own_cpus
> >
> >
> > Changes in V3:
> >
> > perf auxtrace: Add mmap_needed to auxtrace_mmap_params
> > Amended mmap_needed comment
> >
> > perf evlist: Add evlist__add_dummy_on_all_cpus()
> > Amended comment about all CPUs.
> >
> >
> > Changes in V2:
> >
> > Added some Acked-by: Ian Rogers <irogers@...gle.com>
> >
> > libperf evsel: Add perf_evsel__enable_thread()
> > Use perf_cpu_map__for_each_cpu()
> >
> > perf auxtrace: Add mmap_needed to auxtrace_mmap_params
> > Add documentation comment for mmap_needed
> >
> > perf auxtrace: Remove auxtrace_mmap_params__set_idx() per_cpu parameter
> > Fix missing auxtrace_mmap_params__set_idx change
> >
> > libperf evlist: Check nr_mmaps is correct
> > Remove unused code
> >
> > libperf evsel: Add comments for booleans
> > Amend comments
> >
> > perf evlist: Add evlist__add_dummy_on_all_cpus()
> > Rename evlist__add_system_wide -> evlist__add_on_all_cpus
> > Changed patch subject accordingly
> >
> > perf record: Use evlist__add_dummy_on_all_cpus() in record__config_text_poke()
> > Rename evlist__add_system_wide -> evlist__add_on_all_cpus
> > Changed patch subject accordingly
> >
> > perf intel-pt: Use evlist__add_dummy_on_all_cpus() for switch tracking
> > Rename evlist__add_system_wide -> evlist__add_on_all_cpus
> > Changed patch subject accordingly
> >
> >
> > Changes in V1:
> >
> > perf intel-pt: Add a test for system-wide side band
> > New patch
> >
> > libperf evsel: Factor out perf_evsel__ioctl()
> > Dropped because it has been applied.
> >
> > libperf evsel: Add perf_evsel__enable_thread()
> > Rename variable i -> idx
> >
> > perf auxtrace: Do not mix up mmap idx
> > Rename variable cpu to cpu_map_idx
> >
> > perf tools: Allow all_cpus to be a superset of user_requested_cpus
> > Add Acked-by: Ian Rogers <irogers@...gle.com>
> >
> > libperf evlist: Allow mixing per-thread and per-cpu mmaps
> > Fix perf_evlist__nr_mmaps() calculation
> >
> > libperf evlist: Check nr_mmaps is correct
> > New patch
> >
> > libperf evsel: Add comments for booleans
> > New patch
> >
> > perf tools: Allow system-wide events to keep their own CPUs
> > perf tools: Allow system-wide events to keep their own threads
> >
> >
> > Adrian Hunter (15):
> > perf intel-pt: Add a test for system-wide side band
> > perf auxtrace: 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_dummy_on_all_cpus()
> > perf record: Use evlist__add_dummy_on_all_cpus() in record__config_text_poke()
> > perf intel-pt: Use evlist__add_dummy_on_all_cpus() 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
> > libperf evlist: Check nr_mmaps is correct
> > perf stat: Add requires_cpu flag for uncore
> > libperf evsel: Add comments for booleans
> > 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 | 71 ++++++++++++++-------------------
> > tools/lib/perf/include/internal/evsel.h | 11 +++++
> > tools/perf/arch/x86/util/intel-pt.c | 31 ++++++--------
> > tools/perf/builtin-record.c | 39 +++++++-----------
> > tools/perf/builtin-stat.c | 5 +--
> > tools/perf/tests/shell/test_intel_pt.sh | 71 +++++++++++++++++++++++++++++++++
> > tools/perf/util/auxtrace.c | 15 +++++--
> > tools/perf/util/auxtrace.h | 13 ++++--
> > tools/perf/util/evlist.c | 61 +++++++++++++++++++++++++---
> > tools/perf/util/evlist.h | 5 +++
> > tools/perf/util/evsel.c | 1 +
> > tools/perf/util/mmap.c | 4 +-
> > tools/perf/util/parse-events.c | 2 +-
> > 13 files changed, 226 insertions(+), 103 deletions(-)
> > create mode 100755 tools/perf/tests/shell/test_intel_pt.sh
> >
> >
> > Regards
> > Adrian
--
- Arnaldo
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