From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1750812AbdAXG6c (ORCPT <rfc822;w@1wt.eu>);
        Tue, 24 Jan 2017 01:58:32 -0500
Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:39581 "EHLO
        mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK)
        by vger.kernel.org with ESMTP id S1750704AbdAXG6a (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 24 Jan 2017 01:58:30 -0500
Subject: Re: [PATCH v5 0/2] perf probe: add sdt probes arguments into the
 uprobe cmd string
To: Ingo Molnar <mingo@kernel.org>
References: <20161207122610.008da636793d38a39accf29b@kernel.org>
 <20161214000732.1710-1-alexis.berlemont@gmail.com>
 <20161214073656.GB1635@gmail.com>
Cc: Alexis Berlemont <alexis.berlemont@gmail.com>,
        linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@redhat.com,
        acme@kernel.org, alexander.shishkin@linux.intel.com,
        Jiri Olsa <jolsa@redhat.com>,
        Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Date: Tue, 24 Jan 2017 12:28:19 +0530
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.5.1
MIME-Version: 1.0
In-Reply-To: <20161214073656.GB1635@gmail.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-TM-AS-GCONF: 00
X-Content-Scanned: Fidelis XPS MAILER
x-cbid: 17012406-0044-0000-0000-0000025BE393
X-IBM-SpamModules-Scores: 
X-IBM-SpamModules-Versions: BY=3.00006488; HX=3.00000240; KW=3.00000007;
 PH=3.00000004; SC=3.00000200; SDB=6.00811885; UDB=6.00395886; IPR=6.00589302;
 BA=6.00005084; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000;
 ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014021; XFM=3.00000011;
 UTC=2017-01-24 06:58:26
X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused
x-cbparentid: 17012406-0045-0000-0000-00000688E5E6
Message-Id: <5886FB0B.40901@linux.vnet.ibm.com>
X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-01-24_04:,,
 signatures=0
X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=2
 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam
 adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000
 definitions=main-1701240062
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org



On Wednesday 14 December 2016 01:06 PM, Ingo Molnar wrote:
> * Alexis Berlemont <alexis.berlemont@gmail.com> wrote:
>
>> Hi Masami,
>>
>> Many thanks for your mail.
>>
>> Here is another patch set which tries to fix the points you mentioned:
>>
>> * Skip the arguments containing a constant ($123); 
>> * Review the code in charge of the register renaming (search for '%'
>>   and parse it);
>> * Minor changes (print the argument in case of error, skipping, check
>>   the sdt arg type index);
>>
>> Many thanks,
>>
>> Alexis.
>>
>> Alexis Berlemont (2):
>>   perf sdt: add scanning of sdt probles arguments
>>   perf probe: add sdt probes arguments into the uprobe cmd string
> I'd like to hijack this thread to report an SDT oddity - one of my boxen reports 
> lots of SDT tracepoints in 'perf list':
>
>   mem:<addr>[/len][:access]                          [Hardware breakpoint]
>
>   sdt_libc:lll_lock_wait_private                     [SDT event]
>   sdt_libc:longjmp                                   [SDT event]
>   sdt_libc:longjmp_target                            [SDT event]
>   sdt_libc:memory_arena_new                          [SDT event]
>   sdt_libc:memory_arena_retry                        [SDT event]
>   sdt_libc:memory_arena_reuse                        [SDT event]
>   sdt_libc:memory_arena_reuse_free_list              [SDT event]
>   sdt_libc:memory_arena_reuse_wait                   [SDT event]
>   sdt_libc:memory_calloc_retry                       [SDT event]
>   sdt_libc:memory_heap_free                          [SDT event]
>   ...
>
> But none of them work:
>
>   Error:  No permissions to read /sys/kernel/debug/tracing/events/sdt_libc/longjmp
>   Hint:   Try 'sudo mount -o remount,mode=755 /sys/kernel/debug/tracing'
>
>   ...
>
>   Error:  File /sys/kernel/debug/tracing/events/sdt_libc/longjmp not found.
>   Hint:   Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
>
> What kind of patches are required for SDT probes to work?

Hi Ingo,

I suppose you are trying to record SDT events without probing it.
In that case, first put a probe on an event and then try to record
it. For example,

$ ./perf list | grep sdt_
  sdt_glib:main__after_prepare                       [SDT event]
  sdt_glib:main__before_dispatch                     [SDT event]
  ...

$ ./perf record -a -e sdt_glib:main__after_prepare
  event syntax error: 'sdt_glib:main__after_prepare'
                       \___ unknown tracepoint

  Error:  File /sys/kernel/debug/tracing/events/sdt_glib/main__after_prepare not found.
  Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
  ...

$ ./perf probe sdt_glib:main__after_prepare
  Added new events:
    sdt_glib:main__after_prepare (on %main__after_prepare in /usr/lib64/libglib-2.0.so.0.5000.2)
    sdt_glib:main__after_prepare_1 (on %main__after_prepare in /usr/lib64/libglib-2.0.so.0.5000.2)

  You can now use it in all perf tools, such as:

    perf record -e sdt_glib:main__after_prepare_1 -aR sleep 1

$ ./perf record -a -e sdt_glib:main__after_prepare
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.191 MB perf.data ]

-Ravi