kernel/tools/perf/util/evlist.c, branch master

perf stat: Add no-affinity flag

2026-02-10T12:35:28Z

Add flag that disables affinity behavior. Using sched_setaffinity() to place a perf thread on a CPU can avoid certain interprocessor interrupts but may introduce a delay due to the scheduling, particularly on loaded machines. Add a command line option to disable the behavior. This behavior is less present in other tools like `perf record`, as it uses a ring buffer and doesn't make repeated system calls. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Andres Freund Cc: Dapeng Mi Cc: Dr. David Alan Gilbert Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Falcon Cc: Thomas Richter Cc: Yang Li Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Reduce affinity use and move into iterator, fix no affinity

2026-02-10T12:34:44Z

The evlist__for_each_cpu iterator will call sched_setaffitinity when moving between CPUs to avoid IPIs. If only 1 IPI is saved then this may be unprofitable as the delay to get scheduled may be considerable. This may be particularly true if reading an event group in `perf stat` in interval mode. Move the affinity handling completely into the iterator so that a single evlist__use_affinity can determine whether CPU affinities will be used. For `perf record` the change is minimal as the dummy event and the real event will always make the use of affinities the thing to do. In `perf stat`, tool events are ignored and affinities only used if >1 event on the same CPU occur. Determining if affinities are useful is done by evlist__use_affinity which tests per-event whether the event's PMU benefits from affinity use - it is assumed only perf event using PMUs do. Fix a bug where when there are no affinities that the CPU map iterator may reference a CPU not present in the initial evsel. Fix by making the iterator and non-iterator code common. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Andres Freund Cc: Dapeng Mi Cc: Dr. David Alan Gilbert Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Falcon Cc: Thomas Richter Cc: Yang Li Signed-off-by: Arnaldo Carvalho de Melo

perf evlist: Missing TPEBS close in evlist__close()

2026-02-10T12:34:11Z

The libperf evsel close won't close TPEBS events properly. Add a test to do this. The libperf close routine is used in evlist__close() for affinity reasons. Signed-off-by: Ian Rogers Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Andres Freund Cc: Dapeng Mi Cc: Dr. David Alan Gilbert Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Falcon Cc: Thomas Richter Cc: Yang Li 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 tools: Use const for variables receiving str{str,r?chr}() returns

2025-12-17T12:30:37Z

Newer glibc versions return const char for str{str,chr}() where the haystack/s is const so to avoid warnings like these on fedora 44 change some variables to const: 36 8.17 fedora:44 : FAIL gcc version 15.2.1 20251111 (Red Hat 15.2.1-4) (GCC) libbpf.c: In function 'kallsyms_cb': libbpf.c:8489:13: error: assignment discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers] 8489 | res = strstr(sym_name, ".llvm."); Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/20251211221756.96294-4-acme@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Merge deferred user callchains

2025-12-03T05:59:14Z

Save samples with deferred callchains in a separate list and deliver them after merging the user callchains. If users don't want to merge they can set tool->merge_deferred_callchains to false to prevent the behavior. With previous result, now perf script will show the merged callchains. $ perf script ... pwd 2312 121.163435: 249113 cpu/cycles/P: ffffffff845b78d8 __build_id_parse.isra.0+0x218 ([kernel.kallsyms]) ffffffff83bb5bf6 perf_event_mmap+0x2e6 ([kernel.kallsyms]) ffffffff83c31959 mprotect_fixup+0x1e9 ([kernel.kallsyms]) ffffffff83c31dc5 do_mprotect_pkey+0x2b5 ([kernel.kallsyms]) ffffffff83c3206f __x64_sys_mprotect+0x1f ([kernel.kallsyms]) ffffffff845e6692 do_syscall_64+0x62 ([kernel.kallsyms]) ffffffff8360012f entry_SYSCALL_64_after_hwframe+0x76 ([kernel.kallsyms]) 7f18fe337fa7 mprotect+0x7 (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) 7f18fe330e0f _dl_sysdep_start+0x7f (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) 7f18fe331448 _dl_start_user+0x0 (/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2) ... The old output can be get using --no-merge-callchain option. Also perf report can get the user callchain entry at the end. $ perf report --no-children --stdio -q -S __build_id_parse.isra.0 # symbol: __build_id_parse.isra.0 8.40% pwd [kernel.kallsyms] | ---__build_id_parse.isra.0 perf_event_mmap mprotect_fixup do_mprotect_pkey __x64_sys_mprotect do_syscall_64 entry_SYSCALL_64_after_hwframe mprotect _dl_sysdep_start _dl_start_user Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim

perf evlist: Avoid scanning all PMUs for evlist__new_default

2025-10-15T14:59:11Z

Rather than wildcard matching the cycles event specify only the core PMUs. This avoids potentially loading unnecessary uncore PMUs. Signed-off-by: Ian Rogers Tested-by: James Clark Signed-off-by: Namhyung Kim

perf parse-events: Warn if a cpu term is unsupported by a CPU

2025-07-24T20:41:34Z

Factor requested CPU warning out of evlist and into evsel. At the end of adding an event, perform the warning check. To avoid repeatedly testing if the cpu_list is empty, add a local variable. ``` $ perf stat -e cpu_atom/cycles,cpu=1/ -a true WARNING: A requested CPU in '1' is not supported by PMU 'cpu_atom' (CPUs 16-27) for event 'cpu_atom/cycles/' Performance counter stats for 'system wide': cpu_atom/cycles/ 0.000781511 seconds time elapsed ``` Reviewed-by: Thomas Falcon Signed-off-by: Ian Rogers Tested-by: James Clark Link: https://lore.kernel.org/r/20250719030517.1990983-2-irogers@google.com Signed-off-by: Namhyung Kim

perf stat: Move metric list from config to evlist

2025-07-11T19:36:40Z

The rblist of metric_event that then have a list of associated metric_expr is moved out of the stat_config and into the evlist. This is done as part of refactoring things for python, having the state split in two places complicates that implementation. The evlist is doing the harder work of enabling and disabling events, the metrics are needed to compute a value and it doesn't seem unreasonable to hang them from the evlist. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250710235126.1086011-7-irogers@google.com Signed-off-by: Namhyung Kim

perf thread_map: Remove uid options

2025-06-09T18:18:18Z

Now the target doesn't have a uid, it is handled through BPF filters, remove the uid options to thread_map creation. Tidy up the functions used in tests to avoid passing unused arguments. Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250604174545.2853620-11-irogers@google.com Signed-off-by: Namhyung Kim