[perfmon2] Perfmon2 on KVM?

[john s. <sy...@vi...>]

Hello,

Should Perfmon2 be expected to work under Linux's KVM? I'm running the 
latest Perfmon2 patch applied to the Ubuntu Jaunty (9.04) 2.6.28 kernel 
source base. Running the "task" command from the libpfm example code, I 
get the following result from running against "bare metal:"

jspurling@tonto:~/download/perfmon/libpfm-3.7/examples$ ./task ls
sycall base 295
major version 2
minor version 82
[FIXED_CTRL(pmc16)=0xaa pmi0=1 en0=0x2 pmi1=1 en1=0x2 pmi2=1 en2=0x0] 
INSTRUCTIONS_RETIRED UNHALTED_CORE_CYCLES
[FIXED_CTR0(pmd16)]
[FIXED_CTR1(pmd17)]
PMD17               2500652 UNHALTED_CORE_CYCLES
PMD16               3140613 INSTRUCTIONS_RETIRED

However, I get the following running under KVM:
sycall base 
295                                                                                                       

major version 
2                                                                                                       

minor version 
82                                                                                                      

AMD family=6 model=0x2 stepping=0x3 rev=B 
(K7)                                                                       
[PERFSEL0(pmc0)=0x510076 emask=0x76 umask=0x0 os=0 usr=1 inv=0 en=1 
int=1 edge=0                                     
cnt_mask=0] 
CPU_CLK_UNHALTED                                                                                         

[PERFCTR0(pmd0)]                                                                                                      

[PERFSEL1(pmc1)=0x5100c0 emask=0xc0 umask=0x0 os=0 usr=1 inv=0 en=1 
int=1 edge=0 cnt_mask=0] 
RETIRED_INSTRUCTIONS                                                                                     

[PERFCTR1(pmd1)]                                                                                                      

PMD0        271854249967616 
CPU_CLK_UNHALTED                                                                          

PMD1        272507084996608 
RETIRED_INSTRUCTIONS                                                                      


The number of cycles and instructions seems a bit exorbitant. In the 
case of the KVM run, I'm running on a physically different machine whose 
kernel does not have the Perfmon2 patch.

I'm relatively new to both Perfmon and KVM, so it's quite possible that 
I'm missing something very obvious here.

Thanks,
john