kernel/tools/perf/Documentation, branch linux-6.17.y

perf record: Make --buildid-mmap the default

2025-07-25T17:37:56Z

Support for build IDs in mmap2 perf events has been present since Linux v5.12: https://lore.kernel.org/lkml/20210219194619.1780437-1-acme@kernel.org/ Build ID mmap events don't avoid the need to inject build IDs for DSO touched by samples as the build ID cache is populated by perf record. They can avoid some cases of symbol mis-resolution caused by the file system changing from when a sample occurred and when the DSO is sought. Unlike the --buildid-mmap option, this chnage doesn't disable the build ID cache but it does disable the processing of samples looking for DSOs to inject build IDs for. To disable the build ID cache the -B (--no-buildid) option should be used. Making this option the default was raised on the list in: https://lore.kernel.org/linux-perf-users/CAP-5=fXP7jN_QrGUcd55_QH5J-Y-FCaJ6=NaHVtyx0oyNh8_-Q@mail.gmail.com/ Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250724163302.596743-9-irogers@google.com Signed-off-by: Namhyung Kim

perf parse-events: Allow the cpu term to be a PMU or CPU range

2025-07-24T20:41:35Z

On hybrid systems, events like msr/tsc/ will aggregate counts across all CPUs. Often metrics only want a value like msr/tsc/ for the cores on which the metric is being computed. Listing each CPU with terms cpu=0,cpu=1.. is laborious and would need to be encoded for all variations of a CPU model. Allow the cpumask from a PMU to be an argument to the cpu term. For example in the following the cpumask of the cstate_pkg PMU selects the CPUs to count msr/tsc/ counter upon: ``` $ cat /sys/bus/event_source/devices/cstate_pkg/cpumask 0 $ perf stat -A -e 'msr/tsc,cpu=cstate_pkg/' -a sleep 0.1 Performance counter stats for 'system wide': CPU0 252,621,253 msr/tsc,cpu=cstate_pkg/ 0.101184092 seconds time elapsed ``` As the cpu term is now also allowed to be a string, allow it to encode a range of CPUs (a list can't be supported as ',' is already a special token). The "event qualifiers" section of the `perf list` man page is updated to detail the additional behavior. The man page formatting is tidied up in this section, as it was incorrectly appearing within the "parameterized events" section. Reviewed-by: Thomas Falcon Signed-off-by: Ian Rogers Link: https://lore.kernel.org/r/20250719030517.1990983-5-irogers@google.com Signed-off-by: Namhyung Kim

perf: ftrace: add graph tracer options args/retval/retval-hex/retaddr

2025-07-23T00:47:22Z

This change adds support for new funcgraph tracer options funcgraph-args, funcgraph-retval, funcgraph-retval-hex and funcgraph-retaddr. The new added options are: - args : Show function arguments. - retval : Show function return value. - retval-hex : Show function return value in hexadecimal format. - retaddr : Show function return address. # ./perf ftrace -G vfs_write --graph-opts retval,retaddr # tracer: function_graph # # CPU DURATION FUNCTION CALLS # | | | | | | | 5) | mutex_unlock() { /* <-rb_simple_write+0xda/0x150 */ 5) 0.188 us | local_clock(); /* <-lock_release+0x2ad/0x440 ret=0x3bf2a3cf90e */ 5) | rt_mutex_slowunlock() { /* <-rb_simple_write+0xda/0x150 */ 5) | _raw_spin_lock_irqsave() { /* <-rt_mutex_slowunlock+0x4f/0x200 */ 5) 0.123 us | preempt_count_add(); /* <-_raw_spin_lock_irqsave+0x23/0x90 ret=0x0 */ 5) 0.128 us | local_clock(); /* <-__lock_acquire.isra.0+0x17a/0x740 ret=0x3bf2a3cfc8b */ 5) 0.086 us | do_raw_spin_trylock(); /* <-_raw_spin_lock_irqsave+0x4a/0x90 ret=0x1 */ 5) 0.845 us | } /* _raw_spin_lock_irqsave ret=0x292 */ 5) | _raw_spin_unlock_irqrestore() { /* <-rt_mutex_slowunlock+0x191/0x200 */ 5) 0.097 us | local_clock(); /* <-lock_release+0x2ad/0x440 ret=0x3bf2a3cff1f */ 5) 0.086 us | do_raw_spin_unlock(); /* <-_raw_spin_unlock_irqrestore+0x23/0x60 ret=0x1 */ 5) 0.104 us | preempt_count_sub(); /* <-_raw_spin_unlock_irqrestore+0x35/0x60 ret=0x0 */ 5) 0.726 us | } /* _raw_spin_unlock_irqrestore ret=0x80000000 */ 5) 1.881 us | } /* rt_mutex_slowunlock ret=0x0 */ 5) 2.931 us | } /* mutex_unlock ret=0x0 */ Signed-off-by: Changbin Du Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/20250613114048.132336-1-changbin.du@huawei.com Signed-off-by: Namhyung Kim

perf ftrace latency: Add -e option to measure time between two events

2025-07-15T05:51:58Z

In addition to the function latency, it can measure events latencies. Some kernel tracepoints are paired and it's menningful to measure how long it takes between the two events. The latency is tracked for the same thread. Currently it only uses BPF to do the work but it can be lifted later. Instead of having separate a BPF program for each tracepoint, it only uses generic 'event_begin' and 'event_end' programs to attach to any (raw) tracepoints. $ sudo perf ftrace latency -a -b --hide-empty \ -e i915_request_wait_begin,i915_request_wait_end -- sleep 1 # DURATION | COUNT | GRAPH | 256 - 512 us | 4 | ###### | 2 - 4 ms | 2 | ### | 4 - 8 ms | 12 | ################### | 8 - 16 ms | 10 | ################ | # statistics (in usec) total time: 194915 avg time: 6961 max time: 12855 min time: 373 count: 28 Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/20250714052143.342851-1-namhyung@kernel.org Signed-off-by: Namhyung Kim

perf stat: Fix uncore aggregation number

2025-06-27T23:14:10Z

Follow up: lore.kernel.org/CAP-5=fVDF4-qYL1Lm7efgiHk7X=_nw_nEFMBZFMcsnOOJgX4Kg@mail.gmail.com/ The patch adds unit aggregation during evsel merge the aggregated uncore counters. Change the name of the column to `ctrs` and `counters` for json mode. Tested on a 2-socket machine with SNC3, uncore_imc_[0-11] and cpumask="0,120" Before: perf stat -e clockticks -I 1000 --per-socket # time socket cpus counts unit events 1.001085024 S0 1 9615386315 clockticks 1.001085024 S1 1 9614287448 clockticks perf stat -e clockticks -I 1000 --per-node # time node cpus counts unit events 1.001029867 N0 1 3205726984 clockticks 1.001029867 N1 1 3205444421 clockticks 1.001029867 N2 1 3205234018 clockticks 1.001029867 N3 1 3205224660 clockticks 1.001029867 N4 1 3205207213 clockticks 1.001029867 N5 1 3205528246 clockticks After: perf stat -e clockticks -I 1000 --per-socket # time socket ctrs counts unit events 1.001026071 S0 12 9619677996 clockticks 1.001026071 S1 12 9618612614 clockticks perf stat -e clockticks -I 1000 --per-node # time node ctrs counts unit events 1.001027449 N0 4 3207251859 clockticks 1.001027449 N1 4 3207315930 clockticks 1.001027449 N2 4 3206981828 clockticks 1.001027449 N3 4 3206566126 clockticks 1.001027449 N4 4 3206032609 clockticks 1.001027449 N5 4 3205651355 clockticks Tested with JSON output linter: perf test "perf stat JSON output linter" 94: perf stat JSON output linter : Ok Suggested-by: Ian Rogers Reviewed-by: Ian Rogers Signed-off-by: Chun-Tse Shao Link: https://lore.kernel.org/r/20250627201818.479421-1-ctshao@google.com Signed-off-by: Namhyung Kim

tools: Remove libcrypto dependency

2025-06-26T17:51:41Z

Remove all occurrence of libcrypto in the build system. Signed-off-by: Yuzhuo Jing Signed-off-by: Eric Biggers Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/20250625202311.23244-5-ebiggers@kernel.org Signed-off-by: Namhyung Kim

Merge tag 'v6.16-rc3' into perf-tools-next

2025-06-23T04:54:03Z

To get the fixes in libbpf and perf tools. Signed-off-by: Namhyung Kim

perf build: detect support for libbpf's emit_strings option

2025-06-20T21:48:14Z

This creates a config option that detects libbpf's ability to display character arrays as strings, which was just added to the BPF tree (https://git.kernel.org/bpf/bpf-next/c/87c9c79a02b4). To test this change, I built perf (from later in this patch set) with: - static libbpf (default, using source from kernel tree) - dynamic libbpf (LIBBPF_DYNAMIC=1 LIBBPF_INCLUDE=/usr/local/include) For both the static and dynamic versions, I used headers with and without the ".emit_strings" option. I verified that of the four resulting binaries, the two with ".emit_strings" would successfully record BPF_METADATA events, and the two without wouldn't. All four binaries would successfully display BPF_METADATA events, because the relevant bit of libbpf code is only used during "perf record". Signed-off-by: Blake Jones Link: https://lore.kernel.org/r/20250612194939.162730-2-blakejones@google.com Signed-off-by: Namhyung Kim

perf mem: Document new output fields (op, cache, mem, dtlb, snoop)

2025-06-16T17:05:10Z

Update the documentation of the new fields with examples and caveats. Also update the related documentation for AMD IBS. Reviewed-by: Ravi Bangoria Signed-off-by: Namhyung Kim Cc: Adrian Hunter Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20250610005742.2173050-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo

perf trace: Remove --map-dump documentation

2025-06-09T18:18:19Z

The --map-dump option was removed in 5e6da6be3082 ("perf trace: Migrate BPF augmentation to use a skeleton"), this patch removes its remaining documentation. Fixes: 5e6da6be3082 ("perf trace: Migrate BPF augmentation to use a skeleton") Signed-off-by: Howard Chu Link: https://lore.kernel.org/r/20250601173252.717780-1-howardchu95@gmail.com Signed-off-by: Namhyung Kim