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Date: Tue, 24 May 2022 22:01:01 -0700
From: Ian Rogers <irogers@...gle.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
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
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 :-)
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
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