On 25/07/2025 12:59, Leo Yan wrote: > This series extends Perf for fine-grained tracing by using BPF program > to pause and resume AUX tracing. The BPF program can be attached to > tracepoints (including ftrace tracepoints and dynamic tracepoints, like > kprobe, kretprobe, uprobe and uretprobe). Using eBPF to pause/resume AUX tracing seems like a great idea. AFAICT with this patch set, there is just support for pause/resume much like what could be done directly without eBPF, so I wonder if you could share a bit more on how you see this evolving, and what your future plans are? > > The first two patches are changes in kernel - it adds a bpf kfunc which > can be invoked from BPF program. > > The Perf tool implements BPF skeleton program, hooks BPF program into a > perf record session. This is finished by patches 03 ~ 05. > > The patch 06 updates documentation for usage of the new introduced > option '--bpf-aux-pause'. > > This series has been tested on Hikey960 platform with commands: > > perf record -e cs_etm/aux-action=start-paused/ \ > --bpf-aux-pause="kretprobe:p:__arm64_sys_openat,kprobe:r:__arm64_sys_openat,tp:r:sched:sched_switch" \ > -a -- ls > > perf record -e cs_etm/aux-action=start-paused/ \ > --bpf-aux-pause="kretprobe:p:__arm64_sys_openat,kprobe:r:__arm64_sys_openat,tp:r:sched:sched_switch" \ > -i -- ls > > perf record -e cs_etm/aux-action=start-paused/ \ > --bpf-aux-pause="uretprobe:p:/mnt/sort:bubble_sort,uprobe:r:/mnt/sort:bubble_sort" \ > --per-thread -- /mnt/sort > > Note, as the AUX pause operation cannot be inherited by child tasks, it > requires to specify the '-i' option for default mode. Otherwise, the > tool reports an error to remind user to disable inherited mode: > > Failed to update BPF map for auxtrace: Operation not supported. > Try to disable inherit mode with option '-i'. > > Changes in v3: > - Added check "map->type" (Eduard) > - Fixed kfunc with guard(irqsave). > - Link to v2: https://lore.kernel.org/r/20250718-perf_aux_pause_resume_bpf_rebase-v2-0-992557b8fb16@xxxxxxx > > Changes in v2: > - Changed to use BPF kfunc and dropped uAPI (Yonghong). > - Added support uprobe/uretprobe. > - Refined the syntax for trigger points (mainly for trigger action {p:r}). > - Fixed a bug in the BPF program with passing wrong flag. > - Rebased on bpf-next branch. > - Link to v1: https://lore.kernel.org/linux-perf-users/20241215193436.275278-1-leo.yan@xxxxxxx/T/#m10ea3e66bca7418db07c141a14217934f36e3bc8 > > --- > Leo Yan (6): > perf/core: Make perf_event_aux_pause() as external function > bpf: Add bpf_perf_event_aux_pause kfunc > perf: auxtrace: Control AUX pause and resume with BPF > perf: auxtrace: Add BPF userspace program for AUX pause and resume > perf record: Support AUX pause and resume with BPF > perf docs: Document AUX pause and resume with BPF > > include/linux/perf_event.h | 1 + > kernel/events/core.c | 2 +- > kernel/trace/bpf_trace.c | 55 ++++ > tools/perf/Documentation/perf-record.txt | 51 ++++ > tools/perf/Makefile.perf | 1 + > tools/perf/builtin-record.c | 20 +- > tools/perf/util/Build | 4 + > tools/perf/util/auxtrace.h | 43 +++ > tools/perf/util/bpf_auxtrace_pause.c | 408 ++++++++++++++++++++++++++ > tools/perf/util/bpf_skel/auxtrace_pause.bpf.c | 156 ++++++++++ > tools/perf/util/evsel.c | 6 + > tools/perf/util/record.h | 1 + > 12 files changed, 746 insertions(+), 2 deletions(-) > --- > base-commit: 95993dc3039e29dabb9a50d074145d4cb757b08b > change-id: 20250717-perf_aux_pause_resume_bpf_rebase-174c79b0bab5 > > Best regards,
