Re: [PATCH v2 14/16] perf tools: add new mem command for memoryaccess profiling

From: Arnaldo Carvalho de Melo
Date: Tue Nov 06 2012 - 10:50:25 EST


Em Tue, Nov 06, 2012 at 12:44:46PM -0300, Arnaldo Carvalho de Melo escreveu:
> [root@sandy ~]# 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:

# ========
# 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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