On Tue, Jun 24, 2025 at 12:11 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote: > > On Fri, Jun 06, 2025 at 11:12:34PM -0700, Ian Rogers wrote: > > Pipe mode has no header and emits the data as if it were events. The > > dumping of features was controlled by the --header/-I options which > > makes little sense when they are events, normally traced when > > dump_trace is true. Switch to making pipe feature events also be > > traced with detail when other events are. > > I'm not sure I'm following. Are you saying the pipe mode doesn't > support features with --header/-I option? No, in pipe mode it currently shows just PERF_RECORD_FEATURE or PERF_RECORD_ATTR for the details of the events containing these things. The reason being that the dumping is controlled by separate header flags (--header and -I). In patch 1 the commit message shows the before: ``` $ perf record -o - -a sleep 1 | perf script -D -i - ... 0x2c8@pipe [0x54]: event: 80 . . ... raw event: size 84 bytes . 0000: 50 00 00 00 00 00 54 00 05 00 00 00 00 00 00 00 P.....T......... . 0010: 40 00 00 00 36 2e 31 35 2e 72 63 37 2e 67 61 64 @...6.15.rc7.gad . 0020: 32 61 36 39 31 63 39 39 66 62 00 00 00 00 00 00 2a691c99fb...... . 0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ . 0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ . 0050: 00 00 00 00 .... 0 0 0x2c8 [0x54]: PERF_RECORD_FEATURE ``` That is we have a feature "event" but there are no details there to try to be able to understand the feature event. After the change this becomes: ``` $ perf record -o - -a sleep 1 | perf script -D -i - ... 0x2c8@pipe [0x54]: event: 80 . . ... raw event: size 84 bytes . 0000: 50 00 00 00 00 00 54 00 05 00 00 00 00 00 00 00 P.....T......... . 0010: 40 00 00 00 36 2e 31 35 2e 72 63 37 2e 67 61 64 @...6.15.rc7.gad . 0020: 32 61 36 39 31 63 39 39 66 62 00 00 00 00 00 00 2a691c99fb...... . 0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ . 0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ . 0050: 00 00 00 00 .... 0 0 0x2c8 [0x54]: PERF_RECORD_FEATURE, # perf version : 6.15.rc7.gad2a691c99fb ``` So now in the dump trace output I can see this was a feature for perf version and what that value is. There are often multiple PERF_RECORD_FEATURE and PERF_RECORD_ATTR "events" and so the extra trace output helps in being able to work out what's going on. Thanks, Ian > It seems to work for me. > > $ git show > commit be59dba332e1e8edd3e88d991ba0e4795ae2bcb2 (HEAD -> perf-testing) > Author: Ian Rogers <irogers@xxxxxxxxxx> > Date: Tue Jun 17 15:33:56 2025 -0700 > > libperf evsel: Add missed puts and asserts > > A missed evsel__close before evsel__delete was the source of leaking > perf events due to a hybrid test. Add asserts in debug builds so that > this shouldn't happen in the future. Add puts missing on the cpu map > and thread maps. > > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx> > Link: https://lore.kernel.org/r/20250617223356.2752099-4-irogers@xxxxxxxxxx > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx> > > $ ./perf version > perf version 6.16.rc3.gbe59dba332e1 > > $ ./perf record -o- true | ./perf report -i- --header-only > # ======== > # captured on : Tue Jun 24 12:06:38 2025 > # header version : 1 > # data offset : 0 > # data size : 0 > # feat offset : 0 > # ======== > # > # hostname : bangji > # os release : 6.12.20-1rodete1-amd64 > # perf version : 6.16.rc3.gbe59dba332e1 > # arch : x86_64 > # nrcpus online : 4 > # nrcpus avail : 8 > # cpudesc : 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz > # cpuid : GenuineIntel,6,140,1 > # total memory : 32566540 kB > # cmdline : /home/namhyung/project/linux/tools/perf/perf record -o- true > # event : name = cycles:P, , id = { 369, 370, 371, 372 }, type = 0 (PERF_TYPE_HARDWARE), ... > # CPU_TOPOLOGY info available, use -I to display > # NUMA_TOPOLOGY info available, use -I to display > # pmu mappings: cpu = 4, breakpoint = 5, cstate_core = 22, cstate_pkg = 23, hwmon_acpitz = 4294901760, ... > # time of first sample : 0.000000 > # time of last sample : 0.000000 > # sample duration : 0.000 ms > # MEM_TOPOLOGY info available, use -I to display > # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=icelake > # intel_pt pmu capabilities: topa_multiple_entries=1, psb_cyc=1, single_range_output=1, ... > > > > > The attr event in pipe mode had no dumping, wire this up and use the > > existing perf_event_attr fprintf support. > > > > The header's bpf_prog_info or bpf_btf may be empty when written. If > > they are empty just skip writing them to save space. > > These look good to me. > > Thanks, > Namhyung > > > > > Ian Rogers (4): > > perf header: In pipe mode dump features without --header/-I > > perf header: Allow tracing of attr events > > perf header: Display message if BPF/BTF info is empty > > perf header: Don't write empty BPF/BTF info > > > > tools/perf/util/header.c | 46 ++++++++++++++++++++++++++-------------- > > tools/perf/util/header.h | 1 + > > 2 files changed, 31 insertions(+), 16 deletions(-) > > > > -- > > 2.50.0.rc0.604.gd4ff7b7c86-goog > >
