virtualbox.org

Hello,

I am running a 3.8.13-35.1.2.el6uek.x86_64 linux system inside VirtualBox-4.3-4.3.12_93733_el6-1.x86_64.
sar, vmstat etc report the percentage cpu for system about 10% and infrequently increasing to 20 or even higher than 50%

With the command: 'perf top -e cpu-clock' I see that the top kernel function is acpi_pm_read.

Code: Select all

   PerfTop:    7680 irqs/sec  kernel:98.2%  exact:  0.0% [4000Hz cpu-clock],  (all, 2 CPUs)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
    21.38%  [kernel]                          [k] acpi_pm_read                                        
    12.05%  [kernel]                          [k] native_set_pte_at                                   
     8.17%  [kernel]                          [k] clear_page_c                                        
     6.82%  libc-2.12.so                      [.] __strstr_sse2                                       
     6.70%  [kernel]                          [k] finish_task_switch                                  
     6.16%  libc-2.12.so                      [.] _int_malloc                                         
     4.27%  libc-2.12.so                      [.] memchr                                              
     3.62%  perf.3.8.13-35.1.2.el6uek.x86_64  [.] symbols__insert                                     
     3.54%  [kernel]                          [k] tick_nohz_idle_enter

What may be causing this?
Should I switch of acpi?
If so in grub.conf or with vboxmanage?

Regards Hans-Peter

Hi,

The kernel falls back to this (less efficient) clocksource when a better one isn't usable, and I've observed that TSC isn't usable when multiple cpus are presented to a similar Linux guest. It's probably enough to enable another (more efficient) clocksource in the VM, namely HPET - the kernel will pick it over the apci_pm source, and hopefully cpu utilization goes down for you as it did for me.

From the host command line (correct path as needed for your host):

C:\Program Files\Oracle\VirtualBox>VBoxManage.exe modifyvm "<VM name or UUID>" --hpet on

The guest has to be stopped to run this.

Regards,
Mark

virtualbox.org

%sys cpu high: perf top reports high acpi_pm_read

%sys cpu high: perf top reports high acpi_pm_read

Re: %sys cpu high: perf top reports high acpi_pm_read