2012/3/18 Gleb Natapov <gleb@xxxxxxxxxx>:
> On Sun, Mar 18, 2012 at 06:27:53PM +0530, shashank rachamalla wrote:
>> 2012/3/18 Gleb Natapov <gleb@xxxxxxxxxx>:
>> > On Sun, Mar 18, 2012 at 03:48:53PM +0530, shashank rachamalla wrote:
>> >>
>> >> CPU: Core 2, speed 2200.19 MHz (estimated)
>> >> Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a
>> >> unit mask of 0x00 (Unhalted core cycles) count 100000
>> >> CPU_CLK_UNHALT...|
>> >> samples| %|
>> >> ------------------
>> >> 1 100.000 /no-vmlinux
>> >>
>> >>
>> > What happens if you run "perf stat -e cycles a.out"?
>>
>> This is what i get when I run "perf stat ./a.out" ( with --cpu host
>> passed in qemu-kvm )
>>
>> Performance counter stats for './a.out':
>>
>> 954.925996 task-clock-msecs # 0.955 CPUs
>> 23 context-switches # 0.000 M/sec
>> 0 CPU-migrations # 0.000 M/sec
>> 93 page-faults # 0.000 M/sec
>> 2110635735 cycles # 2210.261 M/sec
>> 901816391 instructions # 0.427 IPC
>> 247677 cache-references # 0.259 M/sec
>> 15044 cache-misses # 0.016 M/sec
>>
>> 0.999846560 seconds time elapsed
>>
>> This is without --cpu host ( Note that only software events get monitored )
>>
>> Performance counter stats for './a.out':
>>
>> 913.826372 task-clock-msecs # 0.990 CPUs
>> 13 context-switches # 0.000 M/sec
>> 0 CPU-migrations # 0.000 M/sec
>> 93 page-faults # 0.000 M/sec
>> <not counted> cycles
>> <not counted> instructions
>> <not counted> cache-references
>> <not counted> cache-misses
>>
>> 0.923182044 seconds time elapsed
>>
>> I guess things are working fine with perf. But why not with oprofile ?
>>
> Looks like it. I never tried oprofile. Will try to reproduce your
> problem and see what oprofile is doing.
I am using ubuntu 10.04 with 2.6.32-21-generic kernel as guest and
oprofile 0.9.6.
Also, I have tried to capture kvm-events ( perf patch ) in host while
running oprofile and perf in guest.
Please see the attachment. I have run the tests in three cases for the
around 5 secs.
There are more number of MSR reads and writes in case of perf which I
think is normal. However, there are very few MSR reads and writes with
oprofile. Also, the number of NMI exceptions are too high in case of
oprofile.
>
> --
> Gleb.
# Normal Case ( without any profiling in guest )
Analyze events for all VCPUs:
VM-EXIT Samples Samples% Time% Avg time
IO_INSTRUCTION 1953 69.03% 2.48% 63.20us ( +- 49.77% )
APIC_ACCESS 343 12.12% 0.07% 10.11us ( +- 4.86% )
EXCEPTION_NMI 289 10.22% 0.03% 5.03us ( +- 2.51% )
PENDING_INTERRUPT 81 2.86% 0.00% 1.69us ( +- 1.19% )
CR_ACCESS 77 2.72% 0.01% 6.04us ( +- 6.86% )
HLT 72 2.55% 97.41% 67426.33us ( +- 9.26% )
EXTERNAL_INTERRUPT 14 0.49% 0.01% 19.50us ( +- 22.36% )
# With perf in guest
Analyze events for all VCPUs:
VM-EXIT Samples Samples% Time% Avg time
EXCEPTION_NMI 6906 26.93% 0.62% 4.16us ( +- 1.56% )
MSR_WRITE 5894 22.99% 0.61% 4.83us ( +- 3.51% )
IO_INSTRUCTION 3981 15.53% 2.81% 32.76us ( +- 21.95% )
MSR_READ 2702 10.54% 0.07% 1.14us ( +- 0.38% )
APIC_ACCESS 2370 9.24% 0.30% 5.78us ( +- 1.81% )
INVLPG 2058 8.03% 0.10% 2.17us ( +- 4.98% )
EXTERNAL_INTERRUPT 830 3.24% 0.35% 19.29us ( +- 25.56% )
CR_ACCESS 418 1.63% 0.05% 5.63us ( +- 9.14% )
PENDING_INTERRUPT 372 1.45% 0.01% 1.67us ( +- 0.47% )
HLT 93 0.36% 95.08% 47371.95us ( +- 10.55% )
CPUID 18 0.07% 0.00% 1.28us ( +- 6.54% )
# With oprofile in guest
Analyze events for all VCPUs:
VM-EXIT Samples Samples% Time% Avg time
EXCEPTION_NMI 161092 60.98% 12.48% 3.15us ( +- 0.56% )
INVLPG 94184 35.65% 4.30% 1.85us ( +- 1.08% )
IO_INSTRUCTION 2674 1.01% 2.39% 36.35us ( +- 31.43% )
CR_ACCESS 2658 1.01% 1.05% 16.00us ( +- 3.06% )
APIC_ACCESS 1739 0.66% 0.29% 6.80us ( +- 2.24% )
EXTERNAL_INTERRUPT 1044 0.40% 0.55% 21.58us ( +- 27.84% )
CPUID 539 0.20% 0.02% 1.28us ( +- 2.73% )
PENDING_INTERRUPT 159 0.06% 0.01% 1.73us ( +- 1.09% )
HLT 73 0.03% 78.92% 43963.08us ( +- 12.33% )
MSR_WRITE 7 0.00% 0.00% 23.73us ( +- 69.57% )
MSR_READ 3 0.00% 0.00% 2.74us ( +- 8.44% )
