On Tue, Aug 05, 2025 at 10:16:29PM +0300, Adrian Hunter wrote: > On 30/07/2025 21:26, Leo Yan wrote: > > Hi Adrian, > > > > On Mon, Jul 28, 2025 at 08:02:51PM +0300, Adrian Hunter wrote: > >> 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? > > > > IIUC, here you mean the tool can use `perf probe` to firstly create > > probes, then enable tracepoints as PMU event for AUX pause and resume. > > Yes, like: > > $ sudo perf probe 'do_sys_openat2 how->flags how->mode' > Added new event: > probe:do_sys_openat2 (on do_sys_openat2 with flags=how->flags > mode=how->mode) > > You can now use it in all perf tools, such as: > > perf record -e probe:do_sys_openat2 -aR sleep 1 > > $ sudo perf probe do_sys_openat2%return > Added new event: > probe:do_sys_openat2__return (on do_sys_openat2%return) > > You can now use it in all perf tools, such as: > > perf record -e probe:do_sys_openat2__return -aR sleep 1 > > $ sudo perf record --kcore -e intel_pt/aux-action=start-paused/k -e > probe:do_sys_openat2/aux-action=resume/ --filter='flags==0x98800' -e > probe:do_sys_openat2__return/aux-action=pause/ -- ls
Thanks a lot for sharing the commands. I was able to replicate them using CoreSight. Given that we can achieve the same result without using BPF, I am not sure how useful this series is. It may give us a base for exploring profiling that combines AUX trace and BPF, but I am fine with holding on until we have clear requirements for it. I would get suggestion from you and maintainers before proceeding further. Thanks, Leo
