kernel/tools/perf/Documentation/perf.data-file-format.txt, branch linux-rolling-stable

perf tools: Update header documentation on BPF_PROG_INFO

2025-09-19T15:14:30Z

Update the perf.data file format description on header section HEADER_BPF_PROG_INFO. The information is taken from process_bpf_prog_info() and write_bpf_prog_info() from file util/header.c. Reviewed-by: Jan Polensky Signed-off-by: Thomas Richter Acked-by: Namhyung Kim Acked-by: Sumanth Korikkar Cc: Alexander Gordeev Cc: Heiko Carstens Cc: Vasily Gorbik Signed-off-by: Arnaldo Carvalho de Melo

perf record: Add 8-byte aligned event type PERF_RECORD_COMPRESSED2

2025-05-16T20:31:40Z

The original PERF_RECORD_COMPRESS is not 8-byte aligned, which can cause asan runtime error: # Build with asan $ make -C tools/perf O=/tmp/perf DEBUG=1 EXTRA_CFLAGS="-O0 -g -fno-omit-frame-pointer -fsanitize=undefined" # Test success with many asan runtime errors: $ /tmp/perf/perf test "Zstd perf.data compression/decompression" -vv 83: Zstd perf.data compression/decompression: ... util/session.c:1959:13: runtime error: member access within misaligned address 0x7f69e3f99653 for type 'union perf_event', which requires 13 byte alignment 0x7f69e3f99653: note: pointer points here d0 3a 50 69 44 00 00 00 00 00 08 00 bb 07 00 00 00 00 00 00 44 00 00 00 00 00 00 00 ff 07 00 00 ^ util/session.c:2163:22: runtime error: member access within misaligned address 0x7f69e3f99653 for type 'union perf_event', which requires 8 byte alignment 0x7f69e3f99653: note: pointer points here d0 3a 50 69 44 00 00 00 00 00 08 00 bb 07 00 00 00 00 00 00 44 00 00 00 00 00 00 00 ff 07 00 00 ^ ... Since there is no way to align compressed data in zstd compression, this patch add a new event type `PERF_RECORD_COMPRESSED2`, which adds a field `data_size` to specify the actual compressed data size. The `header.size` contains the total record size, including the padding at the end to make it 8-byte aligned. Tested with `Zstd perf.data compression/decompression` Signed-off-by: Chun-Tse Shao Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ben Gainey Cc: Christophe Leroy Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Leo Yan Cc: Mark Rutland Cc: Namhyung Kim Cc: Nick Terrell Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250303183646.327510-1-ctshao@google.com Signed-off-by: Arnaldo Carvalho de Melo

perf doc: Fix typo in perf.data-file-format.txt

2023-07-28T22:01:16Z

The 'it' should be 'is' here, fix it. Signed-off-by: Xiu Jianfeng Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20230727105001.261420-1-xiujianfeng@huawei.com Signed-off-by: Arnaldo Carvalho de Melo

perf header: Record non-CPU PMU capabilities

2022-06-24T16:18:55Z

PMUs advertise their capabilities via sysfs attribute files but the perf tool currently parses only core(CPU) or hybrid core PMU capabilities. Add support of recording non-core PMU capabilities int perf.data header. Note that a newly proposed HEADER_PMU_CAPS is replacing existing HEADER_HYBRID_CPU_PMU_CAPS. Special care is taken for hybrid core PMUs by writing their capabilities first in the perf.data header to make sure new perf.data file being read by old perf tool does not break. Reviewed-by: Kan Liang Signed-off-by: Ravi Bangoria Acked-by: Namhyung Kim Cc: Ananth Narayan Cc: Andi Kleen Cc: Borislav Petkov Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kim Phillips Cc: Leo Yan Cc: Mark Rutland Cc: Peter Zijlstra Cc: Robert Richter Cc: Sandipan Das Cc: Santosh Shukla Cc: Stephane Eranian Cc: Thomas Gleixner Cc: like.xu.linux@gmail.com Cc: x86@kernel.org Link: https://lore.kernel.org/r/20220604044519.594-6-ravi.bangoria@amd.com Signed-off-by: Arnaldo Carvalho de Melo

perf record: Add finished init event

2022-06-23T14:54:22Z

In preparation for recording sideband events in a virtual machine guest so that they can be injected into a host perf.data file. This is needed to enable injecting events after the initial synthesized user events (that have an all zero id sample) but before regular events. Committer notes: Add entry about PERF_RECORD_FINISHED_INIT to tools/perf/Documentation/perf.data-file-format.txt. Committer testing: Before: # perf report -D | grep FINISHED 0 0x5910 [0x8]: PERF_RECORD_FINISHED_ROUND FINISHED_ROUND events: 1 ( 0.5%) # After: # perf record -- sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.020 MB perf.data (7 samples) ] # perf report -D | grep FINISHED 0 0x5068 [0x8]: PERF_RECORD_FINISHED_INIT: unhandled! 0 0x5390 [0x8]: PERF_RECORD_FINISHED_ROUND FINISHED_ROUND events: 1 ( 0.5%) FINISHED_INIT events: 1 ( 0.5%) # Signed-off-by: Adrian Hunter Acked-by: Ian Rogers Tested-by: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Namhyung Kim Link: https://lore.kernel.org/r/20220610113316.6682-5-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf bpf: Pull in bpf_program__get_prog_info_linear()

2021-11-01T21:16:40Z

To prepare for impending deprecation of libbpf's bpf_program__get_prog_info_linear(), pull in the function and associated helpers into the perf codebase and migrate existing uses to the perf copy. Since libbpf's deprecated definitions will still be visible to perf, it is necessary to rename perf's definitions. Signed-off-by: Dave Marchevsky Acked-by: Andrii Nakryiko Acked-by: Song Liu Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Ingo Molnar Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20211011082031.4148337-4-davemarchevsky@fb.com Signed-off-by: Arnaldo Carvalho de Melo

perf header: Support HYBRID_CPU_PMU_CAPS feature

2021-05-17T13:58:10Z

Perf has supported the CPU_PMU_CAPS feature to display a list of CPU PMU capabilities. But on a hybrid platform, it may have several CPU PMUs (such as "cpu_core" and "cpu_atom"). The CPU_PMU_CAPS feature is hard to extend to support multiple CPU PMUs well if it needs to be compatible for the case of old perf data file + new perf tool. So for better compatibility we now create a new feature HYBRID_CPU_PMU_CAPS in the header. For the perf.data generated on hybrid platform, root@otcpl-adl-s-2:~# perf report --header-only -I # cpu_core pmu capabilities: branches=32, max_precise=3, pmu_name=alderlake_hybrid # cpu_atom pmu capabilities: branches=32, max_precise=3, pmu_name=alderlake_hybrid # missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CPU_PMU_CAPS CLOCK_DATA For the perf.data generated on non-hybrid platform root@kbl-ppc:~# perf report --header-only -I # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake # missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CLOCK_DATA HYBRID_TOPOLOGY HYBRID_CPU_PMU_CAPS Signed-off-by: Jin Yao Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jin Yao Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20210514122948.9472-3-yao.jin@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf header: Support HYBRID_TOPOLOGY feature

2021-05-17T13:55:10Z

It is useful to let the user know about the hybrid topology. Add the HYBRID_TOPOLOGY feature in header to indicate the core CPUs and the atom CPUs. With this patch a perf.data generated on a hybrid platform reports the hybrid CPU list: root@otcpl-adl-s-2:~# perf report --header-only -I ... # hybrid cpu system: # cpu_core cpu list : 0-15 # cpu_atom cpu list : 16-23 For a perf.data generated on a non-hybrid platform, reports a message that HYBRID_TOPOLOGY is missing: root@kbl-ppc:~# perf report --header-only -I ... # missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT COMPRESSED CLOCK_DATA HYBRID_TOPOLOGY Signed-off-by: Jin Yao Acked-by: Jiri Olsa Cc: Alexander Shishkin Cc: Andi Kleen Cc: Jin Yao Cc: Kan Liang Cc: Peter Zijlstra Link: http://lore.kernel.org/lkml/20210514122948.9472-2-yao.jin@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo

perf header: Store clock references for -k/--clockid option

2020-08-06T12:35:06Z

Add a new CLOCK_DATA feature that stores reference times when -k/--clockid option is specified. It contains the clock id and its reference time together with wall clock time taken at the 'same time', both values are in nanoseconds. The format of data is as below: struct { u32 version; /* version = 1 */ u32 clockid; u64 wall_clock_ns; u64 clockid_time_ns; }; This clock reference times will be used in following changes to display wall clock for perf events. It's available only for recording with clockid specified, because it's the only case where we can get reference time to wallclock time. It's can't do that with perf clock yet. Committer testing: $ perf record -h -k Usage: perf record [] [] or: perf record [] -- [] -k, --clockid clockid to use for events, see clock_gettime() $ perf record -k monotonic sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.017 MB perf.data (8 samples) ] $ perf report --header-only | grep clockid -A1 # event : name = cycles:u, , id = { 88815, 88816, 88817, 88818, 88819, 88820, 88821, 88822 }, size = 120, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|PERIOD, read_format = ID, disabled = 1, inherit = 1, exclude_kernel = 1, mmap = 1, comm = 1, freq = 1, enable_on_exec = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1, use_clockid = 1, ksymbol = 1, bpf_event = 1, clockid = 1 # CPU_TOPOLOGY info available, use -I to display -- # clockid frequency: 1000 MHz # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake # clockid: monotonic (1) # reference time: 2020-08-06 09:40:21.619290 = 1596717621.619290 (TOD) = 21931.077673635 (monotonic) $ Original-patch-by: David Ahern Signed-off-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Andi Kleen Cc: David Ahern Cc: Geneviève Bastien Cc: Ian Rogers Cc: Jeremie Galarneau Cc: Michael Petlan Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Wang Nan Link: http://lore.kernel.org/lkml/20200805093444.314999-4-jolsa@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf header: Support CPU PMU capabilities

2020-04-18T12:05:00Z

To stitch LBR call stack, the max LBR information is required. So the CPU PMU capabilities information has to be stored in perf header. Add a new feature HEADER_CPU_PMU_CAPS for CPU PMU capabilities. Retrieve all CPU PMU capabilities, not just max LBR information. Add variable max_branches to facilitate future usage. Committer testing: # ls -la /sys/devices/cpu/caps/ total 0 drwxr-xr-x. 2 root root 0 Apr 17 10:53 . drwxr-xr-x. 6 root root 0 Apr 17 07:02 .. -r--r--r--. 1 root root 4096 Apr 17 10:53 max_precise # # cat /sys/devices/cpu/caps/max_precise 0 # perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.033 MB perf.data (7 samples) ] # # perf report --header-only | egrep 'cpu(desc|.*capabilities)' # cpudesc : AMD Ryzen 5 3600X 6-Core Processor # cpu pmu capabilities: max_precise=0 # And then on an Intel machine: $ ls -la /sys/devices/cpu/caps/ total 0 drwxr-xr-x. 2 root root 0 Apr 17 10:51 . drwxr-xr-x. 6 root root 0 Apr 17 10:04 .. -r--r--r--. 1 root root 4096 Apr 17 11:37 branches -r--r--r--. 1 root root 4096 Apr 17 10:51 max_precise -r--r--r--. 1 root root 4096 Apr 17 11:37 pmu_name $ cat /sys/devices/cpu/caps/max_precise 3 $ cat /sys/devices/cpu/caps/branches 32 $ cat /sys/devices/cpu/caps/pmu_name skylake $ perf record sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ] $ perf report --header-only | egrep 'cpu(desc|.*capabilities)' # cpudesc : Intel(R) Core(TM) i5-7500 CPU @ 3.40GHz # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake $ Signed-off-by: Kan Liang Reviewed-by: Andi Kleen Acked-by: Jiri Olsa Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Alexey Budankov Cc: Mathieu Poirier Cc: Michael Ellerman Cc: Namhyung Kim Cc: Pavel Gerasimov Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Stephane Eranian Cc: Vitaly Slobodskoy Link: http://lore.kernel.org/lkml/20200319202517.23423-3-kan.liang@linux.intel.com Signed-off-by: Arnaldo Carvalho de Melo