kernel.git/tools/perf/builtin-record.c, branch master

perf record: Make logs more readable for event open failures

2026-02-06T14:53:10Z

Since commit ee27476fa3004f83 ("perf record: Skip don't fail for events that don't open"), if a user does not have permission to access a PMU event, perf reports: perf record -e cs_etm// -C 3 -- ls Error: Failure to open event 'cs_etm//u' on PMU 'cs_etm' which will be removed. No fallback found for 'cs_etm//u' for error 13 Error: Failure to open event 'dummy:u' on PMU 'software' which will be removed. No fallback found for 'dummy:u' for error 13 Error: Failure to open any events for recording. The log is not very helpful, as no clear indication of what "error 13" means or how to address the issue. This commit restores evsel__open_strerror() to generate a readable error message and print it out: perf record -e cs_etm// -C 3 -- ls Error: Failure to open event 'cs_etm//' on PMU 'cs_etm' which will be removed. Access to performance monitoring and observability operations is limited. Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open access to performance monitoring and observability operations for processes without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability. More information can be found at 'Perf events and tool security' document: https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html perf_event_paranoid setting is 1: -1: Allow use of (almost) all events by all users Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK >= 0: Disallow raw and ftrace function tracepoint access >= 1: Disallow CPU event access >= 2: Disallow kernel profiling To make the adjusted perf_event_paranoid setting permanent preserve it in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = ) Error: Failure to open event 'dummy:u' on PMU 'software' which will be removed. Access to performance monitoring and observability operations is limited. Consider adjusting /proc/sys/kernel/perf_event_paranoid setting to open access to performance monitoring and observability operations for processes without CAP_PERFMON, CAP_SYS_PTRACE or CAP_SYS_ADMIN Linux capability. More information can be found at 'Perf events and tool security' document: https://www.kernel.org/doc/html/latest/admin-guide/perf-security.html perf_event_paranoid setting is 1: -1: Allow use of (almost) all events by all users Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK >= 0: Disallow raw and ftrace function tracepoint access >= 1: Disallow CPU event access >= 2: Disallow kernel profiling To make the adjusted perf_event_paranoid setting permanent preserve it in /etc/sysctl.conf (e.g. kernel.perf_event_paranoid = ) Error: Failure to open any events for recording. Reviewed-by: Ian Rogers Signed-off-by: Leo Yan Cc: Adrian Hunter Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Signed-off-by: Arnaldo Carvalho de Melo

perf record: Disable inline frames when marking build IDs

2026-01-20T15:56:19Z

Marking DSOs doesn't need inline frames traversing as the inline frames are all part of the same DSO. Disable to improve performance and also to avoid potential issues with dwarf information. Signed-off-by: Ian Rogers Cc: Aditya Bodkhe Cc: Adrian Hunter Cc: Albert Ou Cc: Alexandre Ghiti Cc: Andi Kleen Cc: Athira Rajeev Cc: Chun-Tse Shao Cc: Dmitriy Vyukov Cc: Dr. David Alan Gilbert Cc: Guo Ren Cc: Haibo Xu Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: John Garry Cc: Krzysztof Łopatowski Cc: Leo Yan Cc: Mark Wielaard Cc: Namhyung Kim Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Sergei Trofimovich Cc: Shimin Guo Cc: Stephen Brennan Cc: Thomas Falcon Cc: Will Deacon Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Switch printf("...%s", strerror(errno)) to printf("...%m")

2026-01-14T20:22:50Z

strerror() has thread safety issues, strerror_r() requires stack allocated buffers. Code in perf has already been using the "%m" formatting flag that is a widely support glibc extension to print the current errno's description. Expand the usage of this formatting flag and remove usage of strerror()/strerror_r(). Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Blake Jones Cc: Chun-Tse Shao Cc: Dmitriy Vyukov Cc: Dr. David Alan Gilbert Cc: Haibo Xu Cc: Howard Chu Cc: Ingo Molnar Cc: Jiri Olsa Cc: Leo Yan Cc: Peter Zijlstra Cc: Stephen Brennan Cc: Thomas Falcon Cc: Yunseong Kim Cc: Zhongqiu Han Signed-off-by: Arnaldo Carvalho de Melo

perf record: Split --data-mmap option

2025-12-17T12:30:37Z

Currently -d/--data option controls both PERF_SAMPLE_ADDR bit and perf_event_attr.mmap_data flag. Separate them using new --data-mmap option to support recording only one of them. For data-type profiling, data MMAP is unnecessary but it wastes a lot of space in the ring buffer and data file. Committer testing: On an idle system: root@x1:~# perf record -d -a sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 5.672 MB perf.data (1075 samples) ] root@x1:~# ls -la perf.data -rw-------. 1 root root 5982480 Dec 16 15:34 perf.data root@x1:~# perf evlist -v cpu_atom/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0xa00000000 (cpu_atom/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 cpu_core/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0x400000000 (cpu_core/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|ADDR|CPU|PERIOD|IDENTIFIER|DATA_SRC, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 dummy:u: type: 1 (PERF_TYPE_SOFTWARE), size: 144, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|ADDR|CPU|IDENTIFIER|DATA_SRC, read_format: ID|LOST, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, mmap_data: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, build_id: 1 root@x1:~# Now with just --data-mmap we will not save that much, as only DATA_SRC will not be enabled in sample_type: root@x1:~# perf record --data-mmap -a sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 5.576 MB perf.data (716 samples) ] root@x1:~# ls -la perf.data -rw-------. 1 root root 5880112 Dec 16 15:37 perf.data root@x1:~# perf evlist -v cpu_atom/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0xa00000000 (cpu_atom/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 cpu_core/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0x400000000 (cpu_core/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 dummy:u: type: 1 (PERF_TYPE_SOFTWARE), size: 144, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|IDENTIFIER, read_format: ID|LOST, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, mmap_data: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, build_id: 1 root@x1:~# To complete, just with DATA_SRC, no mmap_data: root@x1:~# perf record --sample-mem-info -a sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.407 MB perf.data (1311 samples) ] root@x1:~# ls -la perf.data -rw-------. 1 root root 1509224 Dec 16 15:40 perf.data root@x1:~# perf evlist -v cpu_atom/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0xa00000000 (cpu_atom/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER|DATA_SRC, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 cpu_core/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 144, config: 0x400000000 (cpu_core/PERF_COUNT_HW_CPU_CYCLES/), { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER|DATA_SRC, read_format: ID|LOST, disabled: 1, freq: 1, precise_ip: 3, sample_id_all: 1 dummy:u: type: 1 (PERF_TYPE_SOFTWARE), size: 144, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|IDENTIFIER|DATA_SRC, read_format: ID|LOST, exclude_kernel: 1, exclude_hv: 1, mmap: 1, comm: 1, task: 1, sample_id_all: 1, exclude_guest: 1, mmap2: 1, comm_exec: 1, ksymbol: 1, bpf_event: 1, build_id: 1 root@x1:~# Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Peter Zijlstra Signed-off-by: Arnaldo Carvalho de Melo

perf build: Remove NO_AUXTRACE build option

2025-11-14T07:03:11Z

The NO_AUXTRACE build option was used when the __get_cpuid feature test failed or if it was provided on the command line. The option no longer avoids a dependency on a library and so having the option is just adding complexity to the code base. Remove the option CONFIG_AUXTRACE from Build files and HAVE_AUXTRACE_SUPPORT by assuming it is always defined. Signed-off-by: Ian Rogers Reviewed-by: James Clark Signed-off-by: Namhyung Kim

perf record: Make sure to update build-ID cache

2025-11-07T01:29:16Z

Recent change on enabling --buildid-mmap by default brought an issue with build-id handling. With build-ID in MMAP2 records, we don't need to save the build-ID table in the header of a perf data file. But the actual file contents still need to be cached in the debug directory for annotation etc. Split the build-ID header processing and caching and make sure perf record to save hit DSOs in the build-ID cache by moving perf_session__cache_build_ids() to the end of the record__ finish_output(). Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim

perf record: skip synthesize event when open evsel failed

2025-10-31T19:01:02Z

When using perf record with the `--overwrite` option, a segmentation fault occurs if an event fails to open. For example: perf record -e cycles-ct -F 1000 -a --overwrite Error: cycles-ct:H: PMU Hardware doesn't support sampling/overflow-interrupts. Try 'perf stat' perf: Segmentation fault #0 0x6466b6 in dump_stack debug.c:366 #1 0x646729 in sighandler_dump_stack debug.c:378 #2 0x453fd1 in sigsegv_handler builtin-record.c:722 #3 0x7f8454e65090 in __restore_rt libc-2.32.so[54090] #4 0x6c5671 in __perf_event__synthesize_id_index synthetic-events.c:1862 #5 0x6c5ac0 in perf_event__synthesize_id_index synthetic-events.c:1943 #6 0x458090 in record__synthesize builtin-record.c:2075 #7 0x45a85a in __cmd_record builtin-record.c:2888 #8 0x45deb6 in cmd_record builtin-record.c:4374 #9 0x4e5e33 in run_builtin perf.c:349 #10 0x4e60bf in handle_internal_command perf.c:401 #11 0x4e6215 in run_argv perf.c:448 #12 0x4e653a in main perf.c:555 #13 0x7f8454e4fa72 in __libc_start_main libc-2.32.so[3ea72] #14 0x43a3ee in _start ??:0 The --overwrite option implies --tail-synthesize, which collects non-sample events reflecting the system status when recording finishes. However, when evsel opening fails (e.g., unsupported event 'cycles-ct'), session->evlist is not initialized and remains NULL. The code unconditionally calls record__synthesize() in the error path, which iterates through the NULL evlist pointer and causes a segfault. To fix it, move the record__synthesize() call inside the error check block, so it's only called when there was no error during recording, ensuring that evlist is properly initialized. Fixes: 4ea648aec019 ("perf record: Add --tail-synthesize option") Signed-off-by: Shuai Xue Signed-off-by: Namhyung Kim

perf record: Use evlist__new_default when no events specified

2025-10-15T14:59:11Z

Rather than distributing the code doing similar things to evlist__new_default, use the one implementation so that paranoia and wildcard scanning can be optimized. Signed-off-by: Ian Rogers Tested-by: James Clark Signed-off-by: Namhyung Kim

perf record: Skip don't fail for events that don't open

2025-10-15T14:59:10Z

Whilst for many tools it is an expected behavior that failure to open a perf event is a failure, ARM decided to name PMU events the same as legacy events and then failed to rename such events on a server uncore SLC PMU. As perf's default behavior when no PMU is specified is to open the event on all PMUs that advertise/"have" the event, this yielded failures when trying to make the priority of legacy and sysfs/json events uniform - something requested by RISC-V and ARM. A legacy event user on ARM hardware may find their event opened on an uncore PMU which for perf record will fail. Arnaldo suggested skipping such events which this patch implements. Rather than have the skipping conditional on running on ARM, the skipping is done on all architectures as such a fundamental behavioral difference could lead to problems with tools built/depending on perf. An example of perf record failing to open events on x86 is: ``` $ perf record -e data_read,cycles,LLC-prefetch-read -a sleep 0.1 Error: Failure to open event 'data_read' on PMU 'uncore_imc_free_running_0' which will be removed. The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (data_read). "dmesg | grep -i perf" may provide additional information. Error: Failure to open event 'data_read' on PMU 'uncore_imc_free_running_1' which will be removed. The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (data_read). "dmesg | grep -i perf" may provide additional information. Error: Failure to open event 'LLC-prefetch-read' on PMU 'cpu' which will be removed. The LLC-prefetch-read event is not supported. [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 2.188 MB perf.data (87 samples) ] $ perf report --stats Aggregated stats: TOTAL events: 17255 MMAP events: 284 ( 1.6%) COMM events: 1961 (11.4%) EXIT events: 1 ( 0.0%) FORK events: 1960 (11.4%) SAMPLE events: 87 ( 0.5%) MMAP2 events: 12836 (74.4%) KSYMBOL events: 83 ( 0.5%) BPF_EVENT events: 36 ( 0.2%) FINISHED_ROUND events: 2 ( 0.0%) ID_INDEX events: 1 ( 0.0%) THREAD_MAP events: 1 ( 0.0%) CPU_MAP events: 1 ( 0.0%) TIME_CONV events: 1 ( 0.0%) FINISHED_INIT events: 1 ( 0.0%) cycles stats: SAMPLE events: 87 ``` If all events fail to open then the perf record will fail: ``` $ perf record -e LLC-prefetch-read true Error: Failure to open event 'LLC-prefetch-read' on PMU 'cpu' which will be removed. The LLC-prefetch-read event is not supported. Error: Failure to open any events for recording ``` As an evlist may have dummy events that open when all command line events fail we ignore dummy events when detecting if at least some events open. This still permits the dummy event on its own to be used as a permission check: ``` $ perf record -e dummy true [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.046 MB perf.data ] ``` but allows failure when a dummy event is implicilty inserted or when there are insufficient permissions to open it: ``` $ perf record -e LLC-prefetch-read -a true Error: Failure to open event 'LLC-prefetch-read' on PMU 'cpu' which will be removed. The LLC-prefetch-read event is not supported. Error: Failure to open any events for recording ``` As the first parsed event in an evlist is marked as tracking, removing this event can remove tracking from the evlist, removing mmap events and breaking symbolization. To avoid this, if a tracking event is removed then the next event has tracking added. The issue with legacy events is that on RISC-V they want the driver to not have mappings from legacy to non-legacy config encodings for each vendor/model due to size, complexity and difficulty to update. It was reported that on ARM Apple-M? CPUs the legacy mapping in the driver was broken and the sysfs/json events should always take precedent, however, it isn't clear this is still the case. It is the case that without working around this issue a legacy event like cycles without a PMU can encode differently than when specified with a PMU - the non-PMU version favoring legacy encodings, the PMU one avoiding legacy encodings. Legacy events are also case sensitive while sysfs/json events are not. The patch removes events and then adjusts the idx value for each evsel. This is done so that the dense xyarrays used for file descriptors, etc. don't contain broken entries. On ARM it could be common following this change to see a lot of warnings for the cycles event due to many ARM PMUs advertising the cycles event (ARM inconsistently have events bus_cycles and then cycles implying CPU cycles, they also sometimes have a cpu_cycles event). As cycles is a popular event, avoid potentially spamming users with error messages on ARM when there are multiple cycles events in the evlist, the error is still shown when verbose is enabled. Prior versions without adding the tracking data and not warning for cycles on ARM was: Suggested-by: Arnaldo Carvalho de Melo Tested-by: James Clark Tested-by: Leo Yan Tested-by: Atish Patra Tested-by: Thomas Richter Signed-off-by: Ian Rogers Signed-off-by: Namhyung Kim

perf stat: Refactor retry/skip/fatal error handling

2025-10-03T19:49:51Z

For the sake of Intel topdown events commit 9eac5612da1c9102 ("perf stat: Don't skip failing group events") changed 'perf stat' error handling making it so that more errors were fatal and didn't report "" events. The change outside of topdown events was unintentional. The notion of "fatal" error handling was introduced in commit e0e6a6ca3ac211cc ("perf stat: Factor out open error handling") and refined in commits like commit cb5ef60067c11cc8 ("perf stat: Error out unsupported group leader immediately") to be an approach for avoiding later assertion failures in the code base. This change fixes those issues and removes the notion of a fatal error on an event. If all events fail to open then a fatal error occurs with the previous fatal error message. This seems to best match the notion of supported events and allowing some errors not to stop 'perf stat', while allowing the truly fatal no event case to terminate the tool early. The evsel->errored flag is only used in the stat code but always just meaning !evsel->supported although there is a comment about it being sticky. Force all evsels to be supported in evsel__init and then clear this when evsel__open fails. When an event is tried the supported is set to true again. This simplifies the notion of whether an evsel is broken. In the get_group_fd code, fail to get a group fd when the evsel isn't supported. If the leader isn't supported then it is also expected that there is no group_fd as the leader will have been skipped. Therefore change the BUG_ON test to be on supported rather than skippable. This corrects the assertion errors that were the reason for the previous fatal error handling. Fixes: 9eac5612da1c9102 ("perf stat: Don't skip failing group events") Reviewed-by: James Clark Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Chun-Tse Shao Cc: Dapeng Mi Cc: Howard Chu Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Falcon Link: https://lore.kernel.org/r/20251002220727.1889799-2-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo