Messages in this thread | | | From | Ian Rogers <> | Date | Tue, 3 May 2022 11:09:30 -0700 | Subject | Re: [PATCH RFC 00/21] perf intel-pt: Better support for perf record --cpu |
| |
On Fri, Apr 22, 2022 at 9:24 AM Adrian Hunter <adrian.hunter@intel.com> wrote: > > 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
Thanks Adrian, I'm very much in favor of this patch set. Can we add some tests for intel-pt? They could be part of the 'perf record' shell test: https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/tree/tools/perf/tests/shell/record.sh?h=perf/core but probably better as there own thing. A command line broken prior to this change would be great!
Aside from testing, we should clean up what dummy CPUs in the cpu maps means. As per: https://lore.kernel.org/linux-perf-users/CAP-5=fWfs2td9nZLGdEBD+C5s=upa_7SORab8tQ7qH=jX--F7w@mail.gmail.com/
I also think landing: https://lore.kernel.org/linux-perf-users/20220503041757.2365696-3-irogers@google.com/ will help as it avoids the all_cpus map containing references to CPUs from PMU sysfs that had been overridden.
Thanks, Ian
| |