Strange reports of perf events on powerpc 83xx

3 messages, 2 authors, 2015-09-02 · open the first message on its own page

Strange reports of perf events on powerpc 83xx

From: leroy christophe <hidden>
Date: 2015-08-27 13:59:06

Hi,

Has anybody already used 'perf' tool on powerpc MPC83xx ?

I have been succesfully using perf on MPC8xx, but on MPC83xx I get 
something strange.

perf record/report reports addresses on user stack, as if it was mixing 
up D accesses and I accesses.

Any idea of what the problem can be ?

# Samples: 8K of event 'cpu-clock'
# Event count (approx.): 2196000000
#
# Overhead  Command       Shared Object       Symbol
# ........  ............  .................. 
............................................
#
      2.62%  perf_reseau4  libpthread-2.18.so  [.] __libc_send
      2.56%  perf_reseau4  [kernel.kallsyms]   [k] __ip_make_skb
      1.62%  perf_reseau4  [kernel.kallsyms]   [k] __ip_append_data.isra.39
      1.55%  perf_reseau4  [kernel.kallsyms]   [k] ip_finish_output
      1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd94
      1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd95
      1.28%  perf_reseau4  [unknown]           [k] 0x7ffffd97
      1.26%  perf_reseau4  [unknown]           [k] 0x7ffffda3
      1.24%  perf_reseau4  [unknown]           [k] 0x7ffffd98
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd92
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd9b
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffdaa
      1.21%  perf_reseau4  [unknown]           [k] 0x7ffffd96
      1.18%  perf_reseau4  [unknown]           [k] 0x7ffffda7
      1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd8d
      1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd99
      1.13%  perf_reseau4  [unknown]           [k] 0x7ffffd90
      1.13%  perf_reseau4  [unknown]           [k] 0x7ffffda2
      1.12%  perf_reseau4  [kernel.kallsyms]   [k] __local_bh_enable_ip
      1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9c
      1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9e
      1.10%  perf_reseau4  [unknown]           [k] 0x7ffffda0
      1.08%  perf_reseau4  [unknown]           [k] 0x7ffffd9f
      1.08%  perf_reseau4  [unknown]           [k] 0x7ffffda6
      1.05%  perf_reseau4  [unknown]           [k] 0x7ffffda8
      1.02%  perf_reseau4  [unknown]           [k] 0x7ffffd9a
      1.01%  perf_reseau4  [unknown]           [k] 0x7ffffdb0
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd89
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd8b
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffdac


Christophe

Re: Strange reports of perf events on powerpc 83xx

From: Joakim Tjernlund <hidden>
Date: 2015-09-02 14:20:45

On Thu, 2015-08-27 at 15:58 +0200, leroy christophe wrote:
Hi,
=20
Has anybody already used 'perf' tool on powerpc MPC83xx ?
=20
I have been succesfully using perf on MPC8xx, but on MPC83xx I get=20
something strange.
=20
perf record/report reports addresses on user stack, as if it was mixing=20
up D accesses and I accesses.
=20
Any idea of what the problem can be ?
We are also experiencing strange addresses on 83xx, did find the cause
of this problem?

We are using Linux 4.1.0
=20
# Samples: 8K of event 'cpu-clock'
# Event count (approx.): 2196000000
#
# Overhead  Command       Shared Object       Symbol
# ........  ............  ..................=20
............................................
#
      2.62%  perf_reseau4  libpthread-2.18.so  [.] __libc_send
      2.56%  perf_reseau4  [kernel.kallsyms]   [k] __ip_make_skb
      1.62%  perf_reseau4  [kernel.kallsyms]   [k] __ip_append_data.isra.=
39
      1.55%  perf_reseau4  [kernel.kallsyms]   [k] ip_finish_output
      1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd94
      1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd95
      1.28%  perf_reseau4  [unknown]           [k] 0x7ffffd97
      1.26%  perf_reseau4  [unknown]           [k] 0x7ffffda3
      1.24%  perf_reseau4  [unknown]           [k] 0x7ffffd98
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd92
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd9b
      1.22%  perf_reseau4  [unknown]           [k] 0x7ffffdaa
      1.21%  perf_reseau4  [unknown]           [k] 0x7ffffd96
      1.18%  perf_reseau4  [unknown]           [k] 0x7ffffda7
      1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd8d
      1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd99
      1.13%  perf_reseau4  [unknown]           [k] 0x7ffffd90
      1.13%  perf_reseau4  [unknown]           [k] 0x7ffffda2
      1.12%  perf_reseau4  [kernel.kallsyms]   [k] __local_bh_enable_ip
      1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9c
      1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9e
      1.10%  perf_reseau4  [unknown]           [k] 0x7ffffda0
      1.08%  perf_reseau4  [unknown]           [k] 0x7ffffd9f
      1.08%  perf_reseau4  [unknown]           [k] 0x7ffffda6
      1.05%  perf_reseau4  [unknown]           [k] 0x7ffffda8
      1.02%  perf_reseau4  [unknown]           [k] 0x7ffffd9a
      1.01%  perf_reseau4  [unknown]           [k] 0x7ffffdb0
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd89
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd8b
      1.00%  perf_reseau4  [unknown]           [k] 0x7ffffdac

Re: Strange reports of perf events on powerpc 83xx

From: christophe leroy <hidden>
Date: 2015-09-02 18:49:03


Le 02/09/2015 16:20, Joakim Tjernlund a écrit :
On Thu, 2015-08-27 at 15:58 +0200, leroy christophe wrote:
quoted
Hi,

Has anybody already used 'perf' tool on powerpc MPC83xx ?

I have been succesfully using perf on MPC8xx, but on MPC83xx I get
something strange.

perf record/report reports addresses on user stack, as if it was mixing
up D accesses and I accesses.

Any idea of what the problem can be ?
We are also experiencing strange addresses on 83xx, did find the cause
of this problem?

We are using Linux 4.1.0
I identified this afternoon that the issue comes from 
perf_instruction_pointer()
which reads SPRN_SIAR instead of using the NIP register from the pt_regs 
struct
According to the MPC8323 reference manual, there is no such register.

I'm looking at the history in order to fully understand the reason.
Looks like PPC_HAVE_PMU_SUPPORT is selected for all PPC_BOOK3S_32 allthought
mpc832x has no PMU.

Christophe
quoted
# Samples: 8K of event 'cpu-clock'
# Event count (approx.): 2196000000
#
# Overhead  Command       Shared Object       Symbol
# ........  ............  ..................
............................................
#
       2.62%  perf_reseau4  libpthread-2.18.so  [.] __libc_send
       2.56%  perf_reseau4  [kernel.kallsyms]   [k] __ip_make_skb
       1.62%  perf_reseau4  [kernel.kallsyms]   [k] __ip_append_data.isra.39
       1.55%  perf_reseau4  [kernel.kallsyms]   [k] ip_finish_output
       1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd94
       1.33%  perf_reseau4  [unknown]           [k] 0x7ffffd95
       1.28%  perf_reseau4  [unknown]           [k] 0x7ffffd97
       1.26%  perf_reseau4  [unknown]           [k] 0x7ffffda3
       1.24%  perf_reseau4  [unknown]           [k] 0x7ffffd98
       1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd92
       1.22%  perf_reseau4  [unknown]           [k] 0x7ffffd9b
       1.22%  perf_reseau4  [unknown]           [k] 0x7ffffdaa
       1.21%  perf_reseau4  [unknown]           [k] 0x7ffffd96
       1.18%  perf_reseau4  [unknown]           [k] 0x7ffffda7
       1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd8d
       1.17%  perf_reseau4  [unknown]           [k] 0x7ffffd99
       1.13%  perf_reseau4  [unknown]           [k] 0x7ffffd90
       1.13%  perf_reseau4  [unknown]           [k] 0x7ffffda2
       1.12%  perf_reseau4  [kernel.kallsyms]   [k] __local_bh_enable_ip
       1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9c
       1.12%  perf_reseau4  [unknown]           [k] 0x7ffffd9e
       1.10%  perf_reseau4  [unknown]           [k] 0x7ffffda0
       1.08%  perf_reseau4  [unknown]           [k] 0x7ffffd9f
       1.08%  perf_reseau4  [unknown]           [k] 0x7ffffda6
       1.05%  perf_reseau4  [unknown]           [k] 0x7ffffda8
       1.02%  perf_reseau4  [unknown]           [k] 0x7ffffd9a
       1.01%  perf_reseau4  [unknown]           [k] 0x7ffffdb0
       1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd89
       1.00%  perf_reseau4  [unknown]           [k] 0x7ffffd8b
       1.00%  perf_reseau4  [unknown]           [k] 0x7ffffdac

---
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