linux-kernel - Re: [PATCH v2] perf trace: Fix missing handling of --call-graph dwarf

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Date:   Mon, 15 Jan 2018 10:11:02 +0100
From:   Thomas-Mich Richter <tmricht@...ux.vnet.ibm.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        brueckner@...ux.vnet.ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com
Subject: Re: [PATCH v2] perf trace: Fix missing handling of --call-graph dwarf

On 01/12/2018 09:02 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Jan 12, 2018 at 01:47:06PM -0300, Arnaldo Carvalho de Melo escreveu:
>> There is still room for improvement, I noticed overriding is not working
>> for the probe event, investigating it now.
> 
> So, I had to fix this another way to get the possibility of overwriting
> the global options (--max-stack, --call-graph) in an specific tracepoint
> event:
> 
> http://git.kernel.org/acme/c/08e26396c6f2
> 
> replaced that HEAD.
> 
> This cset may take some more minutes to show up, just pushed.
> 

Sorry this does *not* work on my s390x.

I have cloned your perf/core tree and above commit is included.
Here is the command I tried:

[root@...60047 perf]# ./perf trace -vv --no-syscalls  --max-stack 4 --call-graph dwarf 
           -e probe_libc:inet_pton -- ping -6 -c 1 ::1
callchain: type DWARF
callchain: stack dump size 8192
------------------------------------------------------------
perf_event_attr:
  type                             2
  size                             112
  config                           0x45f
  { sample_period, sample_freq }   1
  sample_type                      IP|TID|TIME|ADDR|CPU|PERIOD|RAW|DATA_SRC
  disabled                         1
  inherit                          1
  mmap                             1
  comm                             1
  enable_on_exec                   1
  task                             1
  mmap_data                        1
  sample_id_all                    1
  exclude_guest                    1
  mmap2                            1
  comm_exec                        1
  { wakeup_events, wakeup_watermark } 1
------------------------------------------------------------
sys_perf_event_open: pid 6735  cpu 0  group_fd -1  flags 0x8 = 3
sys_perf_event_open: pid 6735  cpu 1  group_fd -1  flags 0x8 = 4
mmap size 2101248B
perf event ring buffer mmapped per cpu
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.070 ms

--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.070/0.070/0.070/0.000 ms
     0.000 probe_libc:inet_pton:(3ffada42060))
[root@...60047 perf]# 

I do miss in sample_type bits for CALLCHAIN, STACK_USER and REG_USER
in the debug output of the perf_event_open() attribute printout.

When I invoke the command with
[root@...60047 perf]# ./perf trace -vv --no-syscalls 
	-e probe_libc:inet_pton/call-graph=dwarf,max-stack=3/ -- ping -6 -c 1 ::1
callchain: type DWARF
callchain: stack dump size 8192
------------------------------------------------------------
perf_event_attr:
  type                             2
  size                             112
  config                           0x45f
  { sample_period, sample_freq }   1
  sample_type                      IP|TID|TIME|CALLCHAIN|CPU|PERIOD|RAW|REGS_USER|STACK_USER
  disabled                         1
  inherit                          1
  mmap                             1
  comm                             1
  enable_on_exec                   1
  task                             1
  sample_id_all                    1
  exclude_guest                    1
  exclude_callchain_user           1
  mmap2                            1
  comm_exec                        1
  { wakeup_events, wakeup_watermark } 1
  sample_regs_user                 0x3ffffffff
  sample_stack_user                8192
  sample_max_stack                 3
------------------------------------------------------------
sys_perf_event_open: pid 6768  cpu 0  group_fd -1  flags 0x8 = 3
sys_perf_event_open: pid 6768  cpu 1  group_fd -1  flags 0x8 = 4
mmap size 528384B
perf event ring buffer mmapped per cpu
PING ::1(::1) 56 data bytes
64 bytes from ::1: icmp_seq=1 ttl=64 time=0.074 ms

--- ::1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.074/0.074/0.074/0.000 ms
[... snip ....]

unwind: _start:ip = 0x2aa1e38457b (0x457b)
     0.000 probe_libc:inet_pton:(3ff9b142060))
                                       __GI___inet_pton (/usr/lib64/libc-2.26.so)
                                       gaih_inet (inlined)
                                       __GI_getaddrinfo (inlined)
                                       main (/usr/bin/ping)
                                       __libc_start_main (/usr/lib64/libc-2.26.so)
                                       _start (/usr/bin/ping)
[root@...60047 perf]# 

I see the proper result as expected.

-- 
Thomas Richter, Dept 3303, IBM LTC Boeblingen Germany
--
Vorsitzende des Aufsichtsrats: Martina Koederitz 
Geschäftsführung: Dirk Wittkopp
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