Re: [RFC] perf record: Add option to print perf_event_open args and return value

[Ravi Bangoria]

On 11/8/19 1:34 PM, Jiri Olsa wrote:
> On Fri, Nov 08, 2019 at 09:29:49AM +0530, Ravi Bangoria wrote:
> > Perf record with verbose=2 already prints this information along with
> > whole lot of other traces which requires lot of scrolling. I thought
> > to show this information in verbose=1 but I fear that it will be too
> > much for level 1. So finally created a new option specifically for
> > printing this.
> >
> > Sample o/p:
> >    $ ./perf record --peo-args -- ls > /dev/null
> >    ------------------------------------------------------------
> >    perf_event_attr:
> >      size                             112
> >      { sample_period, sample_freq }   4000
> >      sample_type                      IP|TID|TIME|PERIOD
> >      read_format                      ID
> >      disabled                         1
> >      inherit                          1
> >      exclude_kernel                   1
> >      mmap                             1
> >      comm                             1
> >      freq                             1
> >      enable_on_exec                   1
> >      task                             1
> >      precise_ip                       3
> >      sample_id_all                    1
> >      exclude_guest                    1
> >      mmap2                            1
> >      comm_exec                        1
> >      ksymbol                          1
> >      bpf_event                        1
> >    ------------------------------------------------------------
> >    sys_perf_event_open: pid 4308  cpu 0  group_fd -1  flags 0x8 = 4
> >    sys_perf_event_open: pid 4308  cpu 1  group_fd -1  flags 0x8 = 5
> >    sys_perf_event_open: pid 4308  cpu 2  group_fd -1  flags 0x8 = 6
> >    sys_perf_event_open: pid 4308  cpu 3  group_fd -1  flags 0x8 = 8
> >    sys_perf_event_open: pid 4308  cpu 4  group_fd -1  flags 0x8 = 9
> >    sys_perf_event_open: pid 4308  cpu 5  group_fd -1  flags 0x8 = 10
> >    sys_perf_event_open: pid 4308  cpu 6  group_fd -1  flags 0x8 = 11
> >    sys_perf_event_open: pid 4308  cpu 7  group_fd -1  flags 0x8 = 12
> >    ------------------------------------------------------------
> >    perf_event_attr:
> >      type                             1
> >      size                             112
> >      config                           0x9
> >      watermark                        1
> >      sample_id_all                    1
> >      bpf_event                        1
> >      { wakeup_events, wakeup_watermark } 1
> >    ------------------------------------------------------------
> >    sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8
> >    sys_perf_event_open failed, error -13
> >    [ perf record: Woken up 1 times to write data ]
> >    [ perf record: Captured and wrote 0.002 MB perf.data (9 samples) ]
> >
> > Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
>
> right, -vv is already poluted ;-) but we have the perf --debug
> option for specific debug:
>
>         --debug
>             Setup debug variable (see list below) in value range (0, 10). Use like: --debug verbose # sets verbose = 1 --debug verbose=2 # sets verbose = 2
>
>                 List of debug variables allowed to set:
>                   verbose          - general debug messages
>                   ordered-events   - ordered events object debug messages
>                   data-convert     - data convert command debug messages
>                   stderr           - write debug output (option -v) to stderr
>                                      in browser mode
>
> so I think something like this would fit better:
>
>    perf --debug event-open[=X] record ...
>    perf --debug perf-event-open[=X] record ...

Thanks Jiri. This looks better. Will respin.