On 28/02/14 07:24, Muthusamy wrote:
Hi,
I am trying to get the memory load latency info using perf, but I am always
getting 0.
Can you please help me in understanding what I am missing. Below are the details
[root@rafa tmp]# ./perf --version
perf version 3.12.11
[root@rafa tmp]# ./perf stat -e r100b pwd ### (I have tried with other data
intensive programs too)
/tmp/cms/tmp
Performance counter stats for 'pwd':
0 r100b
0.000846849 seconds time elapsed
[root@rafa tmp]# uname -a
Linux rafa 2.6.32-431.el6.x86_64 #1 SMP Sun Nov 10 22:19:54 EST 2013 x86_64
x86_64 x86_64 GNU/Linux
[root@rafa tmp]# cat /proc/cpuinfo
processor: 0
vendor_id: GenuineIntel
cpu family: 6
model: 26
model name: Intel(R) Xeon(R) CPU X5550 @ 2.67GHz
stepping
: 5
cpu MHz: 1600.000
cache size: 8192 KB
physical id: 0
siblings: 1
core id: 0
cpu cores: 1
apicid: 0
initial apicid: 0
fpu: yes
fpu_exception: yes
cpuid level: 11
wp: yes
flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm
constant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf
pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2
popcnt lahf_lm ida dts tpr_shadow vnmi flexpriority ept vpid
bogomips: 5333.09
clflush size: 64
cache_alignment: 64
address sizes: 40 bits physical, 48 bits virtual
power management:
processor: 1
vendor_id
: GenuineIntel
cpu family: 6
model: 26
model name: Intel(R) Xeon(R) CPU X5550 @ 2.67GHz
stepping: 5
cpu MHz: 1600.000
cache size: 8192 KB
physical id
: 1
siblings: 1
core id: 0
cpu cores: 1
apicid: 16
initial apicid: 16
fpu: yes
fpu_exception: yes
cpuid level: 11
wp: yes
flags: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36
clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm
constant_tsc arch_perfmon pebs bts rep_good xtopology nonstop_tsc aperfmperf
pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2
popcnt lahf_lm ida dts tpr_shadow vnmi flexpriority ept vpid
bogomips: 5332.56
clflush size: 64
cache_alignment: 64
address sizes: 40 bits physical, 48 bits virtual
power management:
[root@rafa tmp]#
Let me know if any other details are also required and steps on how to get them.
Thanks,
Muthusamy C
Hello Muthusamy,
I have obtained load latency info through perf record + perf report,
but never used perf stat to do that. I don't know if this is what you're
looking for, but maybe you can give this a try.
To capture the latency for an app (say /bin/ls)
# perf mem record /bin/ls
Then, to show the summary of the results (which part of the cache
hierarchy provided the data for the references) you can use:
# perf mem report
Additionally, if you want to know the cost in cycles of every memory
reference captured by PEBS, execute:
# perf mem report -D
in that output, each PERF_RECORD_SAMPLE reflects a sample, and its
weight is the latency in cycles that the CPU was waiting for that reference.
Hope that helps.
Regards.
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