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Performance Comparison of Different Virtual Machines Configurations

Overall CPU usage on a physical server beyond peak port capacity is actually higher than overall CPU usage on virtual machines, while audio quality actually shows a quick downfall on a physical server. So the splitting the load into multiple MCPs in a VM environment will definitely take advantage of hardware resources and will achieve high port capacity with fewer audio quality concerns. There are three different VM configurations on the same hardware spec (counting the dual hex cores, 12 vCPUs in total) that are used for this purpose:

  • 3 VMs in total, 4 vCPU are assigned to each VM, only one MCP installed on one VM.
  • 4 VMs in total, 3 vCPU are assigned to each VM, only one MCP installed on one VM.
  • 6 VMs in total, 2 vCPU are assigned to each VM, only one MCP installed on one VM.

The graph below compares overall system CPU usage.

Figure 14: Comparison of System CPU Usage among different VMs configurations

Overall CPU usage scales linearly against port capacity, regardless of how many VMs are configured.


The two graphs below compare RTP stream quality related Max Jitter and Max Delta on these three different VM configurations:

Figure 15: Comparison of Max Jitter among different VM configurations
Figure 16: Comparison of Max Delta among different VM configurations


To achieve higher port capacity, configure more VMs and assign less vCPU to each VM. With audio quality criteria considered, Genesys recommends 600 ports as peak for six VM configurations. Six VMs with two vCPUs for each VM is the optimal configuration.

Below is the table of IOPS for 6 VM configurations:

Table: Disk IOPS of sum of all 6 VMs of dual hex cores, MP3 only

Ports Overall Disk IOPS (kbps)
Total Reads Writes
120 25.18 0.028 25.15
240 42.75 0.052 42.70
300 51.16 0.004 51.15
360 59.61 0.000 59.61
420 67.04 0.000 67.04
480 74.82 0.000 74.82
540 86.30 0.000 86.30
600 94.11 0.000 94.11
660 102.05 0.000 102.04
720 111.30 0.000 111.29


The graph below compares the two tables of IOPS (Table: Disk IOPS of sum of all 3 VMs of dual hex cores for 3 VMs and Table: Disk IOPS of sum of all 6 VMs of dual hex cores, MP3 only for 6 VMs), on the same hardware spec of dual hex cores:

Figure 18: Comparison of System Disk IOPS among different VMs.
  • System Disk IOPS scales linearly against port capacity, but not related for VM configurations.
  • We ran an additional test with only 1 vCPU assigned to each VM, on a single hex core server Hardware profile 2, with a 6-VMs in total on the one server. We could barely run beyond 150 ports—the single CPU cannot be linearly scaled—which compares with a 3-VMs configuration:
Figure 19: Comparison of System Usage for one vCPU vs two vCPUs VMs configuration


The two graphs below show that both Max Jitter and Max Delta jump significantly beyond 150 ports:

Figure 20: Comparison of Max Jitter for one vCPU vs two vCPUs VMs configuration
Figure 21: Comparison of Max Delta for one vCPU vs two vCPUs VMs configuration

The comparison indicates that MCP doesn’t perform well on a single vCPU VM.

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This page was last modified on July 11, 2018, at 00:47.