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

From: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
To: Jiri Olsa <jolsa@redhat.com>
Cc: acme@kernel.org, linux-kernel@vger.kernel.org,
	Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Subject: Re: [RFC] perf record: Add option to print perf_event_open args and return value
Date: Fri, 8 Nov 2019 14:05:17 +0530	[thread overview]
Message-ID: <9d4831b6-71cc-63db-f48c-2627ad97515b@linux.ibm.com> (raw)
In-Reply-To: <20191108080440.GB28919@krava>

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@linux.ibm.com>
> 
> 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.