kernel.git/tools/perf/util/bpf_off_cpu.c, branch master

perf bpf_counter: Move header declarations into C code

2025-10-01T18:27:02Z

Reduce the API surface that is in bpf_counter.h, this helps compiler analysis like unused static function, makes it easier to set a breakpoint and just makes it easier to see the code is self contained. When code is shared between BPF C code, put it inside HAVE_BPF_SKEL. Move transitively found #includes into appropriate C files. No functional change. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Athira Rajeev Cc: Gabriele Monaco Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Song Liu Cc: Tengda Wu Signed-off-by: Arnaldo Carvalho de Melo

perf record --off-cpu: Add --off-cpu-thresh option

2025-05-06T00:51:54Z

Specify the threshold for dumping offcpu samples with --off-cpu-thresh, the unit is milliseconds. Default value is 500ms. Example: perf record --off-cpu --off-cpu-thresh 824 The example above collects direct off-cpu samples where the off-cpu time is longer than 824ms. Committer testing: After commenting out the end off-cpu dump to have just the ones that are added right after the task is scheduled back, and using a threshould of 1000ms, we see some periods (the 5th column, just before "offcpu-time" in the 'perf script' output) that are over 1000.000.000 nanoseconds: root@number:~# perf record --off-cpu --off-cpu-thresh 10000 ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 3.902 MB perf.data (34335 samples) ] root@number:~# perf script Isolated Web Co 59932 [028] 63839.594437: 1000049427 offcpu-time: 7fe63c7976c2 __syscall_cancel_arch_end+0x0 (/usr/lib64/libc.so.6) 7fe63c78c04c __futex_abstimed_wait_common+0x7c (/usr/lib64/libc.so.6) 7fe63c78e928 pthread_cond_timedwait@@GLIBC_2.3.2+0x178 (/usr/lib64/libc.so.6) 5599974a9fe7 mozilla::detail::ConditionVariableImpl::wait_for(mozilla::detail::MutexImpl&, mozilla::BaseTimeDuration const&)+0xe7 (/usr/lib64/fir> 100000000 [unknown] ([unknown]) swapper 0 [025] 63839.594459: 195724 cycles:P: ffffffffac328270 read_tsc+0x0 ([kernel.kallsyms]) Isolated Web Co 59932 [010] 63839.594466: 1000055278 offcpu-time: 7fe63c7976c2 __syscall_cancel_arch_end+0x0 (/usr/lib64/libc.so.6) 7fe63c78ba24 __syscall_cancel+0x14 (/usr/lib64/libc.so.6) 7fe63c804c4e __poll+0x1e (/usr/lib64/libc.so.6) 7fe633b0d1b8 PollWrapper(_GPollFD*, unsigned int, int) [clone .lto_priv.0]+0xf8 (/usr/lib64/firefox/libxul.so) 10000002c [unknown] ([unknown]) swapper 0 [027] 63839.594475: 134433 cycles:P: ffffffffad4c45d9 irqentry_enter+0x19 ([kernel.kallsyms]) swapper 0 [028] 63839.594499: 215838 cycles:P: ffffffffac39199a switch_mm_irqs_off+0x10a ([kernel.kallsyms]) MediaPD~oder #1 1407676 [027] 63839.594514: 134433 cycles:P: 7f982ef5e69f dct_IV(int*, int, int*)+0x24f (/usr/lib64/libfdk-aac.so.2.0.0) swapper 0 [024] 63839.594524: 267411 cycles:P: ffffffffad4c6ee6 poll_idle+0x56 ([kernel.kallsyms]) MediaSu~sor #75 1093827 [026] 63839.594555: 332652 cycles:P: 55be753ad030 moz_xmalloc+0x200 (/usr/lib64/firefox/firefox) swapper 0 [027] 63839.594616: 160548 cycles:P: ffffffffad144840 menu_select+0x570 ([kernel.kallsyms]) Isolated Web Co 14019 [027] 63839.595120: 1000050178 offcpu-time: 7fc9537cc6c2 __syscall_cancel_arch_end+0x0 (/usr/lib64/libc.so.6) 7fc9537c104c __futex_abstimed_wait_common+0x7c (/usr/lib64/libc.so.6) 7fc9537c3928 pthread_cond_timedwait@@GLIBC_2.3.2+0x178 (/usr/lib64/libc.so.6) 7fc95372a3c8 pt_TimedWait+0xb8 (/usr/lib64/libnspr4.so) 7fc95372a8d8 PR_WaitCondVar+0x68 (/usr/lib64/libnspr4.so) 7fc94afb1f7c WatchdogMain(void*)+0xac (/usr/lib64/firefox/libxul.so) 7fc947498660 [unknown] ([unknown]) 7fc9535fce88 [unknown] ([unknown]) 7fc94b620e60 WatchdogManager::~WatchdogManager()+0x0 (/usr/lib64/firefox/libxul.so) fff8548387f8b48 [unknown] ([unknown]) swapper 0 [003] 63839.595712: 212948 cycles:P: ffffffffacd5b865 acpi_os_read_port+0x55 ([kernel.kallsyms]) Suggested-by: Arnaldo Carvalho de Melo Suggested-by: Ian Rogers Suggested-by: Namhyung Kim Reviewed-by: Ian Rogers Signed-off-by: Howard Chu Tested-by: Arnaldo Carvalho de Melo Tested-by: Gautam Menghani Tested-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241108204137.2444151-2-howardchu95@gmail.com Link: https://lore.kernel.org/r/20250501022809.449767-10-howardchu95@gmail.com Signed-off-by: Arnaldo Carvalho de Melo

perf record --off-cpu: Dump the remaining PERF_SAMPLE_ in sample_type from BPF's stack trace map

2025-05-06T00:51:43Z

Dump the remaining PERF_SAMPLE_ data, as if it is dumping a direct sample. Put the stack trace, tid, off-cpu time and cgroup id into the raw_data section, just like a direct off-cpu sample coming from BPF's bpf_perf_event_output(). This ensures that evsel__parse_sample() correctly parses both direct samples and accumulated samples. Suggested-by: Namhyung Kim Reviewed-by: Ian Rogers Signed-off-by: Howard Chu Tested-by: Arnaldo Carvalho de Melo Tested-by: Gautam Menghani Tested-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241108204137.2444151-10-howardchu95@gmail.com Link: https://lore.kernel.org/r/20250501022809.449767-9-howardchu95@gmail.com Signed-off-by: Arnaldo Carvalho de Melo

perf record --off-cpu: Preparation of off-cpu BPF program

2025-05-06T00:48:20Z

Set the perf_event map in BPF for dumping off-cpu samples, and set the offcpu_thresh to specify the threshold. Reviewed-by: Ian Rogers Signed-off-by: Howard Chu Tested-by: Arnaldo Carvalho de Melo Tested-by: Gautam Menghani Tested-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241108204137.2444151-5-howardchu95@gmail.com Link: https://lore.kernel.org/r/20250501022809.449767-4-howardchu95@gmail.com [ Added some missing iteration variables to off_cpu_config() and fixed up a manually edited patch hunk line boundary line ] Signed-off-by: Arnaldo Carvalho de Melo

perf record --off-cpu: Parse off-cpu event

2025-05-06T00:48:02Z

Parse the off-cpu event using parse_event(), as bpf-output. Call evlist__enable_evsel() on off-cpu event. This fixes the inability to collect direct off-cpu samples on a workload, as reported by Arnaldo Carvalho de Melo . The reason being, workload sets enable_on_exec instead of calling evlist__enable(), but off-cpu event does not attach to an executable and execve won't be called, so the fds from perf_event_open() are not enabled. no-inherit should be set to 1, here's the reason: We update the BPF perf_event map for direct off-cpu sample dumping (in following patches), it executes as follows: bpf_map_update_value() bpf_fd_array_map_update_elem() perf_event_fd_array_get_ptr() perf_event_read_local() In perf_event_read_local(), there is: int perf_event_read_local(struct perf_event *event, u64 *value, u64 *enabled, u64 *running) { ... /* * It must not be an event with inherit set, we cannot read * all child counters from atomic context. */ if (event->attr.inherit) { ret = -EOPNOTSUPP; goto out; } Which means no-inherit has to be true for updating the BPF perf_event map. Moreover, for bpf-output events, we primarily want a system-wide event instead of a per-task event. The reason is that in BPF's bpf_perf_event_output(), BPF uses the CPU index to retrieve the perf_event file descriptor it outputs to. Making a bpf-output event system-wide naturally satisfies this requirement by mapping CPU appropriately. Suggested-by: Namhyung Kim Reviewed-by: Ian Rogers Signed-off-by: Howard Chu Tested-by: Arnaldo Carvalho de Melo Tested-by: Gautam Menghani Tested-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241108204137.2444151-4-howardchu95@gmail.com Link: https://lore.kernel.org/r/20250501022809.449767-3-howardchu95@gmail.com Signed-off-by: Arnaldo Carvalho de Melo

perf record: Fix segfault with --off-cpu when debuginfo is not enabled

2025-01-14T17:57:19Z

When kernel is built without debuginfo, running 'perf record' with --off-cpu results in segfault as below: ./perf record --off-cpu -e dummy sleep 1 libbpf: kernel BTF is missing at '/sys/kernel/btf/vmlinux', was CONFIG_DEBUG_INFO_BTF enabled? libbpf: failed to find '.BTF' ELF section in /lib/modules/6.13.0-rc3+/build/vmlinux libbpf: failed to find valid kernel BTF Segmentation fault (core dumped) The backtrace pointed to: #0 0x00000000100fb17c in btf.type_cnt () #1 0x00000000100fc1a8 in btf_find_by_name_kind () #2 0x00000000100fc38c in btf.find_by_name_kind () #3 0x00000000102ee3ac in off_cpu_prepare () #4 0x000000001002f78c in cmd_record () #5 0x00000000100aee78 in run_builtin () #6 0x00000000100af3e4 in handle_internal_command () #7 0x000000001001004c in main () Code sequence is: static void check_sched_switch_args(void) { struct btf *btf = btf__load_vmlinux_btf(); const struct btf_type *t1, *t2, *t3; u32 type_id; type_id = btf__find_by_name_kind(btf, "btf_trace_sched_switch", BTF_KIND_TYPEDEF); btf__load_vmlinux_btf() fails when CONFIG_DEBUG_INFO_BTF is not enabled. Here bpf__find_by_name_kind() calls btf__type_cnt() with NULL btf value and results in segfault. To fix this, add a check to see if btf is not NULL before invoking bpf__find_by_name_kind(). Reviewed-by: Namhyung Kim Signed-off-by: Athira Rajeev Cc: Adrian Hunter Cc: Disha Goel Cc: Hari Bathini Cc: Ian Rogers Cc: Jiri Olsa Cc: Kajol Jain Cc: Madhavan Srinivasan Link: https://lore.kernel.org/r/20241223135813.8175-1-atrajeev@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo

perf record offcpu: Constify control data for BPF

2024-09-03T14:54:47Z

The control knobs set before loading BPF programs should be declared as 'const volatile' so that it can be optimized by the BPF core. Committer testing: root@x1:~# perf record --off-cpu ^C[ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 1.807 MB perf.data (5645 samples) ] root@x1:~# perf evlist cpu_atom/cycles/P cpu_core/cycles/P offcpu-time dummy:u root@x1:~# perf evlist -v cpu_atom/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0xa00000000, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, inherit: 1, freq: 1, precise_ip: 3, sample_id_all: 1 cpu_core/cycles/P: type: 0 (PERF_TYPE_HARDWARE), size: 136, config: 0x400000000, { sample_period, sample_freq }: 4000, sample_type: IP|TID|TIME|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, inherit: 1, freq: 1, precise_ip: 3, sample_id_all: 1 offcpu-time: type: 1 (software), size: 136, config: 0xa (PERF_COUNT_SW_BPF_OUTPUT), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CALLCHAIN|CPU|PERIOD|IDENTIFIER, read_format: ID|LOST, disabled: 1, inherit: 1, freq: 1, sample_id_all: 1 dummy:u: type: 1 (software), size: 136, config: 0x9 (PERF_COUNT_SW_DUMMY), { sample_period, sample_freq }: 1, sample_type: IP|TID|TIME|CPU|IDENTIFIER, read_format: ID|LOST, inherit: 1, 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 root@x1:~# perf trace -e bpf --max-events 5 perf record --off-cpu 0.000 ( 0.015 ms): :2949124/2949124 bpf(cmd: 36, uattr: 0x7ffefc6dbe30, size: 8) = -1 EOPNOTSUPP (Operation not supported) 0.031 ( 0.115 ms): :2949124/2949124 bpf(cmd: PROG_LOAD, uattr: 0x7ffefc6dbb60, size: 148) = 14 0.159 ( 0.037 ms): :2949124/2949124 bpf(cmd: PROG_LOAD, uattr: 0x7ffefc6dbc20, size: 148) = 14 23.868 ( 0.144 ms): perf/2949124 bpf(cmd: PROG_LOAD, uattr: 0x7ffefc6dbad0, size: 148) = 14 24.027 ( 0.014 ms): perf/2949124 bpf(uattr: 0x7ffefc6dbc80, size: 80) = 14 root@x1:~# Signed-off-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Cc: Song Liu Link: https://lore.kernel.org/r/20240902200515.2103769-6-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf offcpu: Add missed btf_free

2023-10-25T20:38:33Z

Caught by address/leak sanitizer. Signed-off-by: Ian Rogers Cc: K Prateek Nayak Cc: Ravi Bangoria Cc: Sandipan Das Cc: Anshuman Khandual Cc: German Gomez Cc: James Clark Cc: Nick Terrell Cc: Sean Christopherson Cc: Changbin Du Cc: liuwenyu Cc: Yang Jihong Cc: Masami Hiramatsu Cc: Miguel Ojeda Cc: Song Liu Cc: Leo Yan Cc: Kajol Jain Cc: Andi Kleen Cc: Kan Liang Cc: Athira Rajeev Cc: Yanteng Si Cc: Liam Howlett Cc: Paolo Bonzini Link: https://lore.kernel.org/r/20231024222353.3024098-8-irogers@google.com Signed-off-by: Namhyung Kim

perf record: Fix BTF type checks in the off-cpu profiling

2023-09-28T03:45:33Z

The BTF func proto for a tracepoint has one more argument than the actual tracepoint function since it has a context argument at the begining. So it should compare to 5 when the tracepoint has 4 arguments. typedef void (*btf_trace_sched_switch)(void *, bool, struct task_struct *, struct task_struct *, unsigned int); Also, recent change in the perf tool would use a hand-written minimal vmlinux.h to generate BTF in the skeleton. So it won't have the info of the tracepoint. Anyway it should use the kernel's vmlinux BTF to check the type in the kernel. Fixes: b36888f71c85 ("perf record: Handle argument change in sched_switch") Reviewed-by: Ian Rogers Acked-by: Song Liu Cc: Hao Luo CC: bpf@vger.kernel.org Link: https://lore.kernel.org/r/20230922234444.3115821-1-namhyung@kernel.org Signed-off-by: Namhyung Kim

perf off_cpu: Fix a typo in BTF tracepoint name, it should be 'btf_trace_sched_switch'

2022-12-14T14:24:31Z

In BTF, tracepoint definitions have the "btf_trace_" prefix. The off-cpu profiler needs to check the signature of the sched_switch event using that definition. But there's a typo (s/bpf/btf/) so it failed always. Fixes: b36888f71c8542cd ("perf record: Handle argument change in sched_switch") Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: bpf@vger.kernel.org Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Song Liu Link: https://lore.kernel.org/r/20221208182636.524139-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo