linux-kernel - Re: [PATCH v2] perf tool: Provide an option to print perf_event

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Message-ID: <20191112112910.GK9365@kernel.org>
Date:   Tue, 12 Nov 2019 08:29:10 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     Ravi Bangoria <ravi.bangoria@...ux.ibm.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] perf tool: Provide an option to print perf_event_open
 args and return value

Em Fri, Nov 08, 2019 at 12:00:09PM +0100, Jiri Olsa escreveu:
> On Fri, Nov 08, 2019 at 03:11:28PM +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. Introduce
> > an option to print only perf_event_open() arguments and return value.
> > 
> > Sample o/p:
> >   $ ./perf --debug perf-event-open=1 record -- 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@...ux.ibm.com>
> > ---
> > v1->v2:
> >  - man page updates.
> 
> Acked-by: Jiri Olsa <jolsa@...nel.org>

[root@...co ~]# perf test -v python
18: 'import perf' in python                               :
--- start ---
test child forked, pid 19237
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /tmp/build/perf/python/perf.so: undefined symbol: debug_peo_args
test child finished with -1
---- end ----
'import perf' in python: FAILED!
[root@...co ~]#

Please always test your changes using 'perf test', before and after, to
see if some regression is being added. I'm trying to fix this one.

Thanks,

- Arnaldo