KVM Profiling results

["Sundaram, Senthilkumar" <ssundara@xxxxxxxxxxxxxxxx>]

Resending with [kvmarm] in the subject keyword.

 

From: Sundaram, Senthilkumar
Sent: Wednesday, November 07, 2012 11:25 AM
To: kvmarm@xxxxxxxxxxxxxxxxxxxxx
Cc: Sundaram, Senthilkumar
Subject: KVM Profiling results

 

Please refer to the thread titled “Profiling” for how to enable “Perf” profiling. I want to use this thread to focus on results of some early KVM profiling.

 

For the time being I am not able to enable Hardware Events due to some issue with my device tree. However, I am able to capture KVM tracepoint events. Here are some early results

 

Test 1: Run guest through Qemu ( pid 1371). No activity on the guest whatsoever. Even killed some background daemons including telnetd.

 

# perf stat -e "kvm:*" -p 1371

 Performance counter stats for process id '1371':

                  0  kvm:kvm_age_page       
                  0  kvm:kvm_fpu            
                 36  kvm:kvm_mmio           
                  0  kvm:kvm_set_irq        
                 18  kvm:kvm_userspace_exit 
                  0  kvm:kvm_set_spte_hva   
                  0  kvm:kvm_unmap_hva_range
                  0  kvm:kvm_unmap_hva      
                 18  kvm:kvm_wfi            
                  0  kvm:kvm_emulate_cp15_imp
                  0  kvm:kvm_mmio_emulate   
                  0  kvm:kvm_irq_line       
                 19  kvm:kvm_guest_fault    
                 41  kvm:kvm_exit           
                 41  kvm:kvm_entry          

       70.955315534  seconds time elapsed

I have run this multiple times and it seems like all the metrics are always correated.

 

guest_fault, userspace_exit , wfi are always approximately the same.

Mmio, entry, exit are always approximately 2x the guest_fault count

 

This leads me to believe all of these activity is related to mmio emulation. I am curious as to what could be the cause of mmio emulation while there is no activity.  Here is the list of tasks running in the guest.

 

    1 root       0:51 init 
    2 root       0:00 [kthreadd]
    3 root       0:00 [ksoftirqd/0]
    5 root       0:00 [kworker/0:0H]
    6 root       0:01 [kworker/u:0]
    7 root       0:00 [kworker/u:0H]
    8 root       0:00 [migration/0]
    9 root       0:00 [rcu_bh]
   10 root       0:11 [rcu_sched]
   11 root       0:00 [ksoftirqd/1]
   13 root       0:00 [kworker/1:0]
   14 root       0:00 [kworker/1:0H]
   15 root       0:00 [khelper]
   18 root       0:01 [kworker/0:1]
  183 root       0:00 [bdi-default]
  185 root       0:00 [kblockd]
  198 root       0:00 [khubd]
  295 root       0:00 [rpciod]
  304 root       0:00 [kswapd0]
  348 root       0:00 [fsnotify_mark]
  366 root       0:00 [nfsiod]
  409 root       0:00 [khvcd]
  548 root       0:00 [kpsmoused]
  551 root       0:00 [kworker/0:2]
  587 root       0:00 [deferwq]
  699 root       0:00 [kworker/u:2]
 1395 root       0:00 -sh
 1402 root       0:00 ps –a

 

 

Thanks & Regards

Senthil

 

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