kernel/linux.git/tools/perf/bench, branch v7.2-rc1

perf bench: Add --write-size option to sched pipe

2026-06-04T13:11:04+00:00

The default ping-pong uses sizeof(int) (4 bytes) per iteration, which exercises only the pipe-buffer merge path and keeps allocation entirely out of the picture. That makes the bench a useful scheduler / context- switch latency probe but unable to surface anything from the pipe page-allocation hot path. Add a -s/--write-size option that sets the bytes written and read per ping-pong iteration. The buffer is allocated for each side via struct thread_data and replaces the on-stack int previously used. The default remains sizeof(int) so existing invocations are unchanged. With --write-size set above PAGE_SIZE the bench drives anon_pipe_write() through alloc_page() (or the bulk pre-alloc, if the relevant patch is applied), which is what we want when measuring pipe locking and page allocation work. The bench is a ping-pong: both sides call write() before read(), so a single write_size payload must fit entirely in the pipe buffer or both sides deadlock waiting for the other to drain. Resize the pipe via F_SETPIPE_SZ to match write_size (skipped at the sizeof(int) default), and error out cleanly when the request exceeds /proc/sys/fs/pipe-max-size. Committer testing: ⬢ [acme@toolbx perf-tools-next]$ perf bench sched pipe # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 0.915 [sec] 0.915493 usecs/op 1092307 ops/sec ⬢ [acme@toolbx perf-tools-next]$ perf bench sched pipe --write-size 1024 # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 0.891 [sec] 0.891915 usecs/op 1121183 ops/sec ⬢ [acme@toolbx perf-tools-next]$ perf bench sched pipe --write-size 4096 # Running 'sched/pipe' benchmark: # Executed 1000000 pipe operations between two processes Total time: 1.366 [sec] 1.366073 usecs/op 732025 ops/sec ⬢ [acme@toolbx perf-tools-next]$ strace -e fcntl perf bench sched pipe --write-size 4096 # Running 'sched/pipe' benchmark: fcntl(4, F_SETPIPE_SZ, 4096) = 4096 fcntl(6, F_SETPIPE_SZ, 4096) = 4096 ^Cstrace: Process 17840 detached ⬢ [acme@toolbx perf-tools-next]$ strace -e fcntl perf bench sched pipe --write-size 1024 # Running 'sched/pipe' benchmark: fcntl(4, F_SETPIPE_SZ, 1024) = 4096 fcntl(6, F_SETPIPE_SZ, 1024) = 4096 ^Cstrace: Process 17845 detached ⬢ [acme@toolbx perf-tools-next]$ strace -e fcntl perf bench sched pipe # Running 'sched/pipe' benchmark: ^Cstrace: Process 17851 detached ⬢ [acme@toolbx perf-tools-next]$ ⬢ [acme@toolbx perf-tools-next]$ perf bench sched pipe --write-size 1048577 # Running 'sched/pipe' benchmark: --write-size 1048577 exceeds /proc/sys/fs/pipe-max-size ⬢ [acme@toolbx perf-tools-next]$ cat /proc/sys/fs/pipe-max-size 1048576 ⬢ [acme@toolbx perf-tools-next]$ acme@number:~/git/perf-tools-next$ Signed-off-by: Breno Leitao Acked-by: Namhyung Kim Tested-by: Arnaldo Carvalho de Melo Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Mark Rutland Cc: Peter Zijlstra Signed-off-by: Arnaldo Carvalho de Melo

perf build: Move BPF skeleton generation out of Makefile.perf

2026-05-20T20:46:45+00:00

Currently, the top-level Makefile.perf defines a massive global bpf-skel umbrella target that pre-compiles all 12+ BPF skeletons (%.skel.h) upfront before launching sub-makes. This forces unrelated sub-makes to serialize behind bpftool and clang BPF target evaluations, causing parallel build bottlenecks. Furthermore, bench_uprobe.bpf.c lived inside util/bpf_skel/, breaking conceptual directory encapsulation since it is consumed purely by bench/uprobe.c. Refactor the BPF skeletons to better achieve directory isolation: 1. Move tools/perf/util/bpf_skel/bench_uprobe.bpf.c directly into tools/perf/bench/bpf_skel/. 2. Extract the skeleton generation infrastructure out of Makefile.perf into a shared inclusion file tools/perf/bpf_skel.mak. 3. Include bpf_skel.mak locally inside tools/perf/util/Build and tools/perf/bench/Build and bind precise local prerequisites. 4. Safely synchronize the shared bpftool bootstrap and vmlinux.h targets via the conditional prepare: umbrella to avoid parallel sub-make races, while evaluating the actual skeletons completely locally on demand. A later patch will move these targets into bpf_skel.mak. 5. Export CLANG from the global Makefile to ensure accurate tool propagation. 6. Clean up Makefile.perf by stripping the global bpf-skel umbrella target and its SKELETONS list. While removing code from Makefile.perf generally helps build performance, the impact here is minimal. The main motivation for the change is to better encapsulate things in the build and simplify Makefile.perf that has around 50 lines removed. Reviewed-by: Namhyung Kim Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers Tested-by: James Clark Cc: Adrian Hunter Cc: Albert Ou Cc: Alexandre Chartre Cc: Alexandre Ghiti Cc: Andrii Nakryiko Cc: Ankur Arora Cc: Collin Funk Cc: Costa Shulyupin Cc: Daniel Borkmann Cc: Dapeng Mi Cc: David Sterba Cc: Dmitrii Dolgov <9erthalion6@gmail.com> Cc: Eduard Zingerman Cc: Howard Chu Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kumar Kartikeya Dwivedi Cc: Leo Yan Cc: Markus Mayer Cc: Martin KaFai Lau Cc: Nathan Chancellor Cc: Nick Terrell Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Quentin Monnet Cc: Ricky Ringler Cc: Song Liu Cc: Swapnil Sapkal Cc: Thomas Falcon Cc: Tomas Glozar Cc: Yonghong Song Signed-off-by: Arnaldo Carvalho de Melo

perf event: Fix size of synthesized sample with branch stacks

2026-05-20T19:11:30+00:00

Synthesizing branch stacks for Intel-PT highlighted an issue where PERF_SAMPLE_BRANCH_HW_INDEX was assumed to always be set in the perf_event_attr branch_sample_type. This caused an incorrect size calculation. Fix the writing of the nr and hw_idx values during sample event synthesis by passing the branch_sample_type into the sample size and synthesis functions. Also update hardware tracers (Intel PT, ARM SPE, CS-ETM) to retrieve and pass their branch_sample_type dynamically to prevent payload misalignment. Fixes: d3f85437ad6a5511 ("perf evsel: Support PERF_SAMPLE_BRANCH_HW_INDEX") Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Dapeng Mi Cc: Ingo Molnar Cc: James Clark Cc: Kan Liang Cc: Leo Yan Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Thomas Falcon Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Use calloc() where applicable

2026-04-09T02:21:05+00:00

Instead of using zalloc(nr_entries * sizeof_entry) that is what calloc() does. In some places where linux/zalloc.h isn't needed, remove it, add when needed and was getting it indirectly. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf tools: Make more global variables static

2026-04-09T02:21:04+00:00

`make check` will run sparse on the perf code base. A frequent warning is "warning: symbol '...' was not declared. Should it be static?" Go through and make global definitions without declarations static. In some cases it is deliberate due to dlsym accessing the symbol, this change doesn't clean up the missing declarations for perf test suites. Sometimes things can opportunistically be made const. Making somethings static exposed unused functions warnings, so restructuring of ifdefs was necessary for that. These changes reduce the size of the perf binary by 568 bytes. Committer notes: Refreshed the patch, the original one fell thru the cracks, updated the size reduction. Remove the trace-event-scripting.c changes, break the build, noticed with container builds and with sashiko: https://sashiko.dev/#/patchset/20260401215306.2152898-1-acme%40kernel.org Also make two variables static to address another sashiko review comment: https://sashiko.dev/#/patchset/20260402001740.2220481-1-acme%40kernel.org Signed-off-by: Ian Rogers Acked-by: Ankur Arora Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Albert Ou Cc: Alexander Shishkin Cc: Alexandre Ghiti Cc: Athira Rajeev Cc: Guo Ren Cc: Howard Chu Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: Leo Yan Cc: Masami Hiramatsu Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Yujie Liu Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Namhyung Kim

perf bench: Add -t/--threads option to perf bench mem mmap

2026-02-26T18:54:12+00:00

So that it can measure overhead of mmap_lock and/or per-VMA lock contention. $ perf bench mem mmap -f demand -l 1000 -t 1 # Running 'mem/mmap' benchmark: # function 'demand' (Demand loaded mmap()) # Copying 1MB bytes ... 2.786858 GB/sec $ perf bench mem mmap -f demand -l 1000 -t 2 # Running 'mem/mmap' benchmark: # function 'demand' (Demand loaded mmap()) # Copying 1MB bytes ... 1.624468 GB/sec/thread ( +- 0.30% ) $ perf bench mem mmap -f demand -l 1000 -t 3 # Running 'mem/mmap' benchmark: # function 'demand' (Demand loaded mmap()) # Copying 1MB bytes ... 1.493068 GB/sec/thread ( +- 0.15% ) $ perf bench mem mmap -f demand -l 1000 -t 4 # Running 'mem/mmap' benchmark: # function 'demand' (Demand loaded mmap()) # Copying 1MB bytes ... 1.006087 GB/sec/thread ( +- 0.41% ) Reviewed-by: Ankur Arora Reviewed-by: James Clark Signed-off-by: Namhyung Kim

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

2026-01-14T20:22:50+00:00

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: Don't read build-ids from non-regular files

2025-11-26T18:13:38+00:00

Simplify the build ID reading code by removing the non-blocking option. Having to pass the correct option to this function was fragile and a mistake would result in a hang, see the linked fix. Furthermore, compressed files are always opened blocking anyway, ignoring the non-blocking option. We also don't expect to read build IDs from non-regular files. The only hits to this function that are non-regular are devices that won't be elf files with build IDs, for example "/dev/dri/renderD129". Now instead of opening these as non-blocking and failing to read, we skip them. Even if something like a pipe or character device did have a build ID, I don't think it would have worked because you need to call read() in a loop, check for -EAGAIN and handle timeouts to make non-blocking reads work. Link: https://lore.kernel.org/linux-perf-users/20251022-james-perf-fix-dso-block-v1-1-c4faab150546@linaro.org/ Signed-off-by: James Clark Signed-off-by: Namhyung Kim

perf auxtrace: Remove errno.h from auxtrace.h and fix transitive dependencies

2025-11-14T07:03:11+00:00

errno.h isn't used in auxtrace.h so remove it and fix build failures caused by transitive dependencies through auxtrace.h on errno.h. Signed-off-by: Ian Rogers Reviewed-by: James Clark Signed-off-by: Namhyung Kim

Merge tag 'x86_cleanups_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-10-11T17:51:14+00:00

Pull x86 cleanups from Borislav Petkov: - Simplify inline asm flag output operands now that the minimum compiler version supports the =@ccCOND syntax - Remove a bunch of AS_* Kconfig symbols which detect assembler support for various instruction mnemonics now that the minimum assembler version supports them all - The usual cleanups all over the place * tag 'x86_cleanups_for_v6.18_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/asm: Remove code depending on __GCC_ASM_FLAG_OUTPUTS__ x86/sgx: Use ENCLS mnemonic in x86/mtrr: Remove license boilerplate text with bad FSF address x86/asm: Use RDPKRU and WRPKRU mnemonics in x86/idle: Use MONITORX and MWAITX mnemonics in x86/entry/fred: Push __KERNEL_CS directly x86/kconfig: Remove CONFIG_AS_AVX512 crypto: x86 - Remove CONFIG_AS_VPCLMULQDQ crypto: X86 - Remove CONFIG_AS_VAES crypto: x86 - Remove CONFIG_AS_GFNI x86/kconfig: Drop unused and needless config X86_64_SMP