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From "Nitin Mehta (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CLOUDSTACK-5352) CPU cap calculated incorrectly for VMs on XenServer hosts
Date Wed, 04 Dec 2013 23:01:35 GMT

     [ https://issues.apache.org/jira/browse/CLOUDSTACK-5352?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Nitin Mehta resolved CLOUDSTACK-5352.
-------------------------------------

    Resolution: Fixed

> CPU cap calculated incorrectly for VMs on XenServer hosts
> ---------------------------------------------------------
>
>                 Key: CLOUDSTACK-5352
>                 URL: https://issues.apache.org/jira/browse/CLOUDSTACK-5352
>             Project: CloudStack
>          Issue Type: Bug
>      Security Level: Public(Anyone can view this level - this is the default.) 
>    Affects Versions: 4.2.0
>            Reporter: Nitin Mehta
>            Assignee: Nitin Mehta
>            Priority: Critical
>             Fix For: 4.3.0
>
>
> The CPU cap assigned to VMs on XenServer hosts (via VCPUs-params parameter) is not calculated
correctly. The assigned values are too low and can result in performance problems. This seems
related to CPU overprovisioning. The assigned CPU cap is approximately the expected cap /
CPU overprovisioning value. The customer is using CloudStack 4.2.0 with XenServer 6.1. On
the customer environment they have several VMs that were created before upgrading to 4.2.0
from 3.0.6 and never rebooted, and those VMs appear to have the expected CPU cap.
> I see similar results on a CS 4.2.1 setup with a XS 6.2 host with 1x E31220L CPU –
2x physical cores / 4x logical cores (with hyperthreading) at 2.20GHz – 8800 MHz total (confirmed
in op_host_capacity), a Compute Offering with 2200 MHz and 4 cores gives a VM with:
> [root@csdemo-xen2 ~]# xe vm-list params=name-label,uuid,VCPUs-params name-label=i-2-87-VM
> uuid ( RO) : 7cd5893e-728a-a0f3-c2cf-f3464cb8b9cb
> name-label ( RW): i-2-87-VM
> VCPUs-params (MRW): weight: 84; cap: 131
> And with a Compute Offering with 2200 MHz and 1 core gives a VM with:
> [root@csdemo-xen2 ~]# xe vm-list params=name-label,uuid,VCPUs-params name-label=i-2-87-VM
> uuid ( RO) : c17cd63a-f6d5-8f76-d7f1-eb34d574e0dd
> name-label ( RW): i-2-87-VM
> VCPUs-params (MRW): weight: 84; cap: 32
> The configured cap does not make sense in either example. In this environment, cpu.overprovisioning.factor
is 3 for the cluster and 1 in Global Settings. In example 1 the cap should be:
> 2200 * 0.99 * 4 / 2200 * 100
> = 396
> But it is:
> 2200 * 0.99 * 4 / (3*2200) * 100
> = 132
> For example 2 it should be:
> 2200 * 0.99 * 1 / 2200 * 100
> = 99
> But it is:
> 2200 * 0.99 * 1 / (3*2200) * 100



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