Re: [PATCH 1/1] perf trace: Collect sys_nanosleep first argument

[Arnaldo Carvalho de Melo]

On Wed, Feb 21, 2024 at 09:15:01AM -0800, Ian Rogers wrote:
> On Wed, Feb 21, 2024 at 9:04 AM Arnaldo Carvalho de Melo
> <acme@xxxxxxxxxx> wrote:
> >
> > That is a 'struct timespec' passed from userspace to the kernel as we
> > can see with a system wide syscall tracing:
> >
> >   root@number:~# perf trace -e nanosleep
> >        0.000 (10.102 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >       38.924 (10.077 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      100.177 (10.107 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      139.171 (10.063 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      200.603 (10.105 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      239.399 (10.064 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      300.994 (10.096 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      339.584 (10.067 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      401.335 (10.057 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      439.758 (10.166 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      501.814 (10.110 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      539.983 (10.227 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      602.284 (10.199 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      640.208 (10.105 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      702.662 (10.163 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      740.440 (10.107 ms): podman/2195174 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >      802.993 (10.159 ms): podman/9150 nanosleep(rqtp: { .tv_sec: 0, .tv_nsec: 10000000 })                   = 0
> >   ^Croot@number:~# strace -p 9150 -e nanosleep
> >
> > If we then use the ptrace method to look at that podman process:
> >
> >   root@number:~# strace -p 9150 -e nanosleep
> >   strace: Process 9150 attached
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   nanosleep({tv_sec=0, tv_nsec=10000000}, NULL) = 0
> >   ^Cstrace: Process 9150 detached
> >   root@number:~#
> >
> > With some changes we can get something closer to the strace output,
> > still in system wide mode:
> >
> >   root@number:~# perf config trace.show_arg_names=false
> >   root@number:~# perf config trace.show_duration=false
> >   root@number:~# perf config trace.show_timestamp=false
> >   root@number:~# perf config trace.show_zeros=true
> >   root@number:~# perf config trace.args_alignment=0
> >   root@number:~# perf trace -e nanosleep --max-events=10
> >   podman/2195174 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/9150 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/2195174 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/9150 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/2195174 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/9150 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/2195174 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/9150 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/2195174 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   podman/9150 nanosleep({ .tv_sec: 0, .tv_nsec: 10000000 }, NULL) = 0
> >   root@number:~#
> >   root@number:~# perf config
> >   trace.show_arg_names=false
> >   trace.show_duration=false
> >   trace.show_timestamp=false
> >   trace.show_zeros=true
> >   trace.args_alignment=0
> >   root@number:~# cat ~/.perfconfig
> >   # this file is auto-generated.
> >   [trace]
> >         show_arg_names = false
> >         show_duration = false
> >         show_timestamp = false
> >         show_zeros = true
> >         args_alignment = 0
> >   root@number:~#
> >
> > This will not get reused by any other syscall as nanosleep is the only
> > one to have as its first argument a 'struct timespec" pointer argument
> > passed from userspace to the kernel:
> >
> >   root@number:~# grep timespec /sys/kernel/tracing/events/syscalls/sys_enter_*/format | grep offset:16
> >   /sys/kernel/tracing/events/syscalls/sys_enter_nanosleep/format:       field:struct __kernel_timespec * rqtp;  offset:16;      size:8; signed:0;
> >   root@number:~#
> >
> > BTF based pretty printing will simplify all this, but then lets just get
> > the low hanging fruits first.
> >
> > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Cc: Ian Rogers <irogers@xxxxxxxxxx>
> > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> 
> v2? https://lore.kernel.org/lkml/Zbq72dJRpOlfRWnf@xxxxxxxxxx/

Nope, I thought I hadn't submitted and when doing a

  git rebase perf-tools-next/perf-tools-next


It was rebased, so I thought I really hadn't submitted it and sent it.

- Arnaldo