Yaoping Ruan

Are clouds ready for large distributed applications

Cloud computing carries the promise of providing powerful new models and abstractions that could transform the way IT services are delivered today. In order to establish the readiness of clouds to deliver meaningful enterprise-class IT services, we identify three key issues that ought to be addressed as first priority from the perspective of potential cloud users: how to deploy large-scale distributed services, how to deliver high availability services, and how to perform problem resolution on the cloud. We analyze multiple sources of publicly available data to establish cloud user expectations and compare against the current state of cloud offerings, with a focus on contrasting the different requirements from two classes of users -- the individual and the enterprise. Through this process, our initial findings indicate that while clouds are ready to support usage scenarios for individual users, there are still rich areas of future research to be explored to enable clouds to support large distributed applications such as those found in enterprise.

Do commodity SMT processors need more OS research

The availability of Simultaneous Multithreading (SMT) in commodity processors such as the Pentium 4 (P4) has raised interest among OS researchers. While earlier simulation studies of SMT suggested exciting performance potential, observed improvement on the P4 has been much more restrained, raising the hope that OS research can help bridge the gap. We argue that OS research for current commodity Simultaneous Multithreading (SMT) processors is unlikely to yield significant benefits. In general, we find that SMT processor simulations were optimistic about cache and memory performance characteristics, while overlooking the OS overheads of SMT kernels versus uniprocessor kernels. Using measurement and analysis on actual hardware, we find that little opportunity exists for realistic performance gains on commodity SMT beyond what is currently achieved.