Cloud computing is a new computing paradigm that aims to transform computing
services into a utility, just as providing electricity in a “pay-as-you-go”
manner. Data centers are increasingly adopting virtualization technology for the
purpose of server consolidation, flexible resource management and better fault
tolerance. Virtualization-based cloud services host networked applications in virtual
machines (VMs), with each VM provided the desired amount of resources
using resource isolation mechanisms.
Effective network performance isolation is fundamental to data centers, which
offers significant benefit of performance predictability for applications. This research
is application-driven. We study how network performance isolation can be
achieved for latency-sensitive cloud applications. For media streaming applications,
network performance isolation means both predicable network bandwidth
and low-jittered network latency. The current resource sharing methods for VMs
mainly focus on resource proportional share, whereas ignore the fact that I/O latency
in VM-hosted platforms is mostly related to resource provisioning rate. The
resource isolation with only quantitative promise does not sufficiently guarantee
performance isolation. Even the VM is allocated with adequate resources such as
CPU time and network bandwidth, problems such as network jitter (variation in
packet delays) can still happen if the resources are provisioned at inappropriate
moments. So in order to achieve performance isolation, the problem is not only
how many/much resources each VM gets, but more importantly whether the resources are provisioned in a timely manner. How to guarantee both requirements
to be achieved in resource allocation is challenging.
This thesis systematically analyzes the causes of unpredictable network latency
in VM-hosted platforms, with both technical discussion and experimental
illustration. We identify that the varied network latency is jointly caused by
VMM CPU scheduler and network traffic shaper, and then address the problem
in these two parts. In our solutions, we consider the design goals of resource
provisioning rate and resource proportionality as two orthogonal dimensions. In
the hypervisor, a proportional share CPU scheduler with soft real-time support
is proposed to guarantee predictable scheduling delay; in network traffic shaper,
we introduce the concept of smooth window to smooth packet delay and apply
closed-loop feedback control to maintain network bandwidth consumption.
The solutions are implemented in Xen 4.1.0 and Linux 2.6.32.13, which are
both the latest versions when this research was conducted. Extensive experiments
have been carried out using both real-life applications and low-level benchmarks.
Testing results show that the proposed solutions can effectively guarantee network
performance isolation, by achieving both predefined network bandwidth and low-jittered
network latency. / published_or_final_version / Computer Science / Master / Master of Philosophy
| Identifer | oai:union.ndltd.org:HKU/oai:hub.hku.hk:10722/174498 |
| Date | January 2011 |
| Creators | Cheng, Luwei., 程芦伟. |
| Contributors | Wang, CL |
| Publisher | The University of Hong Kong (Pokfulam, Hong Kong) |
| Source Sets | Hong Kong University Theses |
| Language | English |
| Detected Language | English |
| Type | PG_Thesis |
| Source | http://hub.hku.hk/bib/B47753183 |
| Rights | The author retains all proprietary rights, (such as patent rights) and the right to use in future works., Creative Commons: Attribution 3.0 Hong Kong License |
| Relation | HKU Theses Online (HKUTO) |
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