linux-kernel - Re: [PATCH v2 14/16] perf tools: add new mem command for memory access profiling

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Date:	Tue, 6 Nov 2012 16:57:59 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...e.hu" <mingo@...e.hu>,
	"ak@...ux.intel.com" <ak@...ux.intel.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung.kim@....com>
Subject: Re: [PATCH v2 14/16] perf tools: add new mem command for memory
 access profiling

On Tue, Nov 6, 2012 at 4:50 PM, Arnaldo Carvalho de Melo
<acme@...stprotocols.net> wrote:
> Em Tue, Nov 06, 2012 at 12:44:46PM -0300, Arnaldo Carvalho de Melo escreveu:
>> [root@...dy ~]# perf record -g -a -e cpu/mem-stores/
>> ^C[ perf record: Woken up 25 times to write data ]
>> [ perf record: Captured and wrote 7.419 MB perf.data (~324160 samples) ]
>>
>> Yay, got some numbers.
>
> But then the results out of:
>
> $ perf mem -t load rep --stdio
>
> Are bogus at least on the callchains:
>
I think it's because we are not using the period in the hist_entry but
the cost and there
is no cost for stores.

I think you should start with loads and no callchain. I am interested
in your toughts on how to
fix the data symbol resolution problem in perf. In V2, I modified the
kernel to at least
help perf distinguish MAP__FUNCTION from MAP__VARIABLE. But there is
still something
wrong.


> # ========
> # captured on: Tue Nov  6 12:46:21 2012
> # hostname : sandy.ghostprotocols.net
> # os release : 3.7.0-rc2+
> # perf version : 3.7.rc4.gfaa41f
> # arch : x86_64
> # nrcpus online : 8
> # nrcpus avail : 8
> # cpudesc : Intel(R) Core(TM) i7-2920XM CPU @ 2.50GHz
> # cpuid : GenuineIntel,6,42,7
> # total memory : 16220228 kB
> # cmdline : /home/acme/bin/perf record -g -a -e cpu/mem-stores/
> # event : name = cpu/mem-stores/, type = 4, config = 0x2cd, config1 = 0x0, config2 = 0x0, excl_usr = 0, excl_kern = 0, excl_ho
> # HEADER_CPU_TOPOLOGY info available, use -I to display
> # HEADER_NUMA_TOPOLOGY info available, use -I to display
> # pmu mappings: cpu = 4, software = 1, tracepoint = 2, uncore_cbox_0 = 6, uncore_cbox_1 = 7, uncore_cbox_2 = 8, uncore_cbox_3
> # ========
> #
> # Samples: 98  of event 'cpu/mem-stores/'
> # Total cost : 98
> # Sort order : cost,mem,sym,dso,symbol_daddr,dso_daddr,snoop,tlb,locked
> #
> # Overhead      Samples     Cost             Memory access                                          Symbol               Share
> # ........  ...........  .......  ........................  ..............................................  ..................
> #
>     19.39%           19      N/A                            [k] csd_unlock                                  [kernel.kallsyms]
>             |
>             --- csd_unlock
>                |
>                |--6242.11%-- generic_smp_call_function_single_interrupt
>                |          smp_call_function_single_interrupt
>                |          call_function_single_interrupt
>                |          cpuidle_enter
>                |          cpuidle_enter_state
>                |          cpuidle_idle_call
>                |          cpu_idle
>                |          |
>                |          |--85.08%-- start_secondary
>                |          |
>                |           --14.92%-- rest_init
>                |                     start_kernel
>                |                     x86_64_start_reservations
>                |                     x86_64_start_kernel
>                |
>                |--100.00%-- smp_call_function_single_interrupt
>                |          call_function_single_interrupt
>                |          cpuidle_enter
>                |          cpuidle_enter_state
>                |          cpuidle_idle_call
>                |          cpu_idle
>                |          start_secondary
>                 --97088126703734472704.00%-- [...]
>
>      5.10%            5      N/A                            [k] _raw_spin_lock_irqsave                      [kernel.kallsyms]
>             |
>
>
>
> Ideas?
>
> - Arnaldo
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