[one-users] Very high unavailable service

[Erico Augusto Cavalcanti Guedes]

Dears,

I 'm running Squid Web Cache Proxy server on Ubuntu Server 12.04 VMs
(kernel 3.2.0-23-generic-pae), OpenNebula 3.4.
My private cloud is composed by one frontend and three nodes. VMs are
running on that 3 nodes, initially one by node.
Outside cloud, there are 2 hosts, one working as web clients and another as
web server, using Web Polygraph Benchmakring Tool.

The goal of tests is stress Squid cache running on VMs.
When same test is executed outside the cloud, using the three nodes as
Physical Machines, there are 100% of cache service availability.
Nevertheless, when cache service is provided by VMs, nothing better than
45% of service availability is reached.
Web clients do not receive responses from squid when it is running on VMs
in 55% of the time.

I have monitored load average of VMs and PMs where VMs are been executed.
First load average field reaches 15 after some hours of tests on VMs, and 3
on physical machines.
Furthermore, there is a set of processes, called migration/X, that are
champions in CPU TIME when VMs are in execution. A sample:

top - 20:01:38 up 1 day,  3:36,  1 user,  load average: 5.50, 5.47, 4.20

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+    TIME COMMAND

   13 root      RT   0     0    0    0 S    0  0.0 408:27.25 408:27
migration/2
    8 root      RT   0     0    0    0 S    0  0.0 404:13.63 404:13
migration/1
    6 root      RT   0     0    0    0 S    0  0.0 401:36.78 401:36
migration/0
   17 root      RT   0     0    0    0 S    0  0.0 400:59.10 400:59
migration/3


It isn't possible to offer web cache service via VMs in the way the service is
behaving, with so small availability.

So, my questions:

1. Does anybody has experienced a similar problem of unresponsive service?
(Whatever service).
2. How to state the bootleneck that is overloading the system, so that it
can be minimized?

Thanks a lot,

Erico.
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