de. However, it still faces several chal- lenges with regard to performance, security, privacy, and interoper- ability. In the following, we discuss the challenges from these aspects: Guaranteed performance: Compared to the dedicated resource allocation in traditional compute model, cloud computing dynam- ically allocates resources on demand. While this is a key feature that enables multiplexing and elasticity, it also introduces serious concern on the application perceived performance. To provide 2.1 Cloud Computing Table 2.1 Cloud computing: benefits and risks. Cloud type Benefits Drawbacks Public Low investment in the short Security: multitenancy and run (pay-as-you-use) transfers over the Internet Highly scalable Quicker service to market Privacy and reliability [18] Private More control and reliability Higher cost: heavy invest in Higher security hardware, administration Higher performance and maintenance Must comply with strict regulations Hybrid Operational flexibility: can Security, privacy and leverage both public and integrity concerns private cloud Scalability: run bursty workloads on the public cloud Cost-effective guaranteed performance, not only the compute resources (e.g., CPU and memory) should be allocated sufficiently, but also the networking resources (e.g., bandwidth and low latency) should be satisfied. Many existing cloud platform uses virtualization to provide isolated compute resources. However, the networking is still shared in a best effort manner across all the tenants, which can become a severe bottleneck when the network is congested. In addition, sharing the same physical server may also introduce additional delay due to context switching. The provider needs to have ways to monitor applications' performance SO that the service- level agreement (SLA) can be met. Security and privacy: Data integrity and security is a big challenge for cloud platforms, especially for public cloud providers. Cus- tomers' data are competitive assets, and it is sensitive. Encrypting everything in the cloud