Guest VM Running Slow and is not Able to Use All the CPUs Assigned to it on ODA

Asset ID:	1-72-1928868.1
Update Date:	2014-09-23
Keywords:

Solution Type Problem Resolution Sure

Solution 1928868.1 : Guest VM Running Slow and is not Able to Use All the CPUs Assigned to it on ODA

Applies to:

Oracle Database Appliance - Version All Versions to All Versions [Release All Releases]
Information in this document applies to any platform.

Symptoms

After creating Guest VM on ODA VM setup, they are running very slow.

The top command in guest VM shows following:

top - 07:51:49 up 11 days, 12:42, 1 user, load average: 3.22, 4.20, 3.22
Tasks: 519 total, xx running, 518 sleeping, 0 stopped, 0 zombie
Cpu(s): 30%us, 40%sy, 0.0%ni, 30%id, 1.2%wa, 0.0%hi, 0.0%si, 60 %st <<<<<<<< %st will be aroung 60 to 80 which is actually
Mem: 32488228k total, 31498624k used, 989604k free, 514032k buffers
Swap: 20477948k total, 26192k used, 20451756k free, 10637544k cached

% st = steal (time given to other DomU instances)

Show the percentage of time spent in involuntary wait by the virtual CPU or CPUs while the hypervisor was servicing another virtual processor.

Following is the VM info from oakcli command from DOM1 ODA BASE :

$ oakcli show vm

NAME NODENUM MEMORY VCPU STATE REPOSITORY

ovp-v-webpd2 0 26624 8 ONLINE samplerepo

$ oakcli show vm ovp-v-webpd2

Resource: ovp-v-webpd2
AutoStart : restore
CPUPriority : 100
Disks : |file:/OVS/Repositories/samplerepo/
VirtualMachines/ovp-v-webpd2/680974
dcc11748bd8d1f9cc790a042cf.img,xvda
,w||file:/OVS/Repositories/samplere
po/VirtualMachines/ovp-v-webpd2/dis
k2.img,xvdb,w|
Domain : XEN_PVM
ExpectedState : online
FailOver : true
IsSharedRepo : true
Keyboard : en-us
MaxMemory : 26624
MaxVcpu : 8
Memory : 26624
Mouse : OS_DEFAULT
Name : ovp-v-webpd2
Networks : |type=netfront,bridge=virt1|
NodeNumStart : 0
OS : OL_5
PrefNodeNum : 1
PrivateIP : None
ProcessorCap : 100
RepoName : samplerepo
State : Online
TemplateName : otml_wls_master
Vcpu : 8
cpupool : default-unpinned-pool
vncport : None

Following is the xmtop output from Dom 0:

xentop - 07:26:04 Xen 4.1.3OVM
3 domains: 1 running, 2 blocked, 0 paused, 0 crashed, 0 dying, 0 shutdown
Mem: 268424744k total, 68771236k used, 199653508k free CPUs: 32 @ 2893MHz

NAME STATE CPU(sec) CPU(%) MEM(k) MEM(%)
Domain-0 -----r 1245936 115.5 4189296 1.6 ...

oakDom1 --b--- 381946 27.9 33296332 12.4 ...

ovp-v-webp --b--- 10022 80 27262976 10.2 ... <<<<<<<<<<<<< We can see the CPU % is even less then 100 whereas it shoud be in thousands.

xm sched-credit from Dom 0:

$ xm sched-credit
Name ID Weight Cap
Domain-0 0 65535 0
oakDom1 1 256 0
ovp-v-webpd2 3 256 100 <<<<<<<<<<<<<< The CPU CAP is set to 100

Changes

A new guest VM was imported and created in ODA virtualized machine.

Cause

CPU_CAP for the guest VM is set to 100 which means regardless of CPU assigned to this virtual machine, it will only use 1 CPU.

Solution

> Execute following command to dynamically change the CPU_CAP from DOM 0:

$ xm sched-credit -d <vm name> -c 0

> Also change the following file for permanently changing the CPU_CAP for virtual machine:

/OVS/Repositories/samplerepo/VirtualMachines/<vm name>/vm.cfg

change :

cpu_cap = 100

cpu_cap = 0

A new internal unpublished bug has been created so that cpu_cap can be set to 0 using oakcli command line itself. Currently it does not allow this to set it to 0.

Bug 19593517 - LNX64-11.2-CMT : INCORRECT CPU CAP SETTINGS

References

<BUG:19593517> - LNX64-11.2-CMT : INCORRECT CPU CAP SETTINGS

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