Description of problem:
I created two cpu profiles, one with QoS that have limitation value 50 and second that have limitation value 25, and I attach this profiles to vm one by one, but I see that values for quota and period under dumpxml stay the same.
I set bug under mom, because I know that we use mom policy to apply quota and period for vm.

Version-Release number of selected component (if applicable):
rhevm-3.5.0-0.27.el6ev.noarch
vdsm-4.16.8.1-4.el7ev.x86_64
mom-0.4.1-4.el7ev.noarch

How reproducible:
Always

Steps to Reproduce:
1. Create two Cpu QoS under the same datacenter one with limitation value 25 and second with 50
<qoss>
<qos type="cpu" href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916/qoss/2571eeea-25a7-4b09-9c37-d82591733f26" id="2571eeea-25a7-4b09-9c37-d82591733f26">
<name>test_1</name>
<data_center href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916" id="f8f5eaee-8fd0-4b45-87db-62d61b03a916"/>
<cpu_limit>50</cpu_limit>
</qos>
<qos type="cpu" href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916/qoss/883d876e-2038-4cd4-8c35-e9b52f2f4380" id="883d876e-2038-4cd4-8c35-e9b52f2f4380">
<name>test_2</name>
<data_center href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916" id="f8f5eaee-8fd0-4b45-87db-62d61b03a916"/>
<cpu_limit>25</cpu_limit>
</qos>
</qoss>
2. Create two cpu profile with different QoS in the same cluster
<cpu_profiles>
<cpu_profile href= "/ovirt-engine/api/cpuprofiles/5be5c0b7-5b91-4ac4-9d53-ef6f987bff05" id="5be5c0b7-5b91-4ac4-9d53-ef6f987bff05">
<name>test_1</name>
<qos href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916/qoss/2571eeea-25a7-4b09-9c37-d82591733f26" id="2571eeea-25a7-4b09-9c37-d82591733f26"/>
<cluster href= "/ovirt-engine/api/clusters/67866b36-fd68-4106-8758-34cf31b0c3d4" id="67866b36-fd68-4106-8758-34cf31b0c3d4"/>
</cpu_profile>
<cpu_profile href= "/ovirt-engine/api/cpuprofiles/b015da68-b7a5-4a4b-8389-5cbc8ce58f73" id="b015da68-b7a5-4a4b-8389-5cbc8ce58f73">
<name>test_2</name>
<qos href= "/ovirt-engine/api/datacenters/f8f5eaee-8fd0-4b45-87db-62d61b03a916/qoss/883d876e-2038-4cd4-8c35-e9b52f2f4380" id="883d876e-2038-4cd4-8c35-e9b52f2f4380"/>
<cluster href= "/ovirt-engine/api/clusters/67866b36-fd68-4106-8758-34cf31b0c3d4" id="67866b36-fd68-4106-8758-34cf31b0c3d4"/>
</cpu_profile>
</cpu_profiles>
3. Create some vm, and run it first with first QoS and after with second.

First run:

<cpu_profile href= "/ovirt-engine/api/cpuprofiles/5be5c0b7-5b91-4ac4-9d53-ef6f987bff05" id="5be5c0b7-5b91-4ac4-9d53-ef6f987bff05"/>

dumpxml
<vcpu placement='static' current='4'>32</vcpu>
  <cputune>
    <shares>1020</shares>
    <period>12500</period>
    <quota>25000</quota>
  </cputune>

Second run:
<cpu_profile href= "/ovirt-engine/api/cpuprofiles/b015da68-b7a5-4a4b-8389-5cbc8ce58f73" id="b015da68-b7a5-4a4b-8389-5cbc8ce58f73"/>

dumpxml
<vcpu placement='static' current='4'>32</vcpu>
  <cputune>
    <shares>1020</shares>
    <period>12500</period>
    <quota>25000</quota>
  </cputune>

Actual results:
<quota> and <period> under cpu_tunning have the same values under dumpxml, for different limitation value

Expected results:
<quota> and <period> have different values under different limitations

Additional info:
ok, I will start with this that not really understand why we use this kind of formula:
period = anchor / #NumOfCpuInHost
quota = (anchor*(#userSelection/100)) / #numOfVcpusInVm
why we need this anchor, and why we change period time(default 1000000)
I played a little with values of period and quota and virsh create, and limitation work pretty well for formula:
period = default_value
quota = period * (pcpu/vcpu) * (limitation/100)
I check it on vm with 4 cpu's and on host with 8 cpu's
with limitation 10, 25 and 50
From some reason the same proportion, but with small period work not precious or  not work at all(seems to me like bug in cgroups)