Chei-Yol Kim

Inter-domain socket communications supporting high performance and full binary compatibility on Xen

Communication performance between two processes in their own domains on the same physical machine gets improved but it does not reach our expectation. This paper presents the design and implementation of high-performance inter-domain communication mechanism, called XWAY, that maintains binary compatibility for applications written in standard socket interface. As a result of our survey, we found that three overheads mainly contribute to the poor performance; those are TCP/IP processing cost in each domain, page flipping overhead, and long communication path between both sides of a socket. XWAY achieves high performance by bypassing TCP/IP stacks, avoiding page flipping overhead, and providing a direct, accelerated communication path between domains in the same machine. Moreover, we introduce the XWAY socket architecture to support full binary compatibility with as little effort as possible. We implemented our design on Xen 3.0.3-0 with Linux kernel 2.6.16.29, and evaluated basic performance, the speed of file transfer, DBT-1 benchmark, and binary compatibility using binary image of real socket applications. In our tests, we have proved that XWAY realizes the high performance that is comparable to UNIX domain socket and ensures full binary compatibility. The basic performance of XWAY, measured with netperf, shows minimum latency of 15.6 usec and peak bandwidth of 4.7Gbps, which is superior to that of native TCP socket. We have also examined whether several popular applications using TCP socket can be executed on XWAY with their own binary images. Those applications worked perfectly well.

Implementation and evaluation of EXT3NS multimedia file system

The EXT3NS is a scalable file system designed to handle video streaming workload in large-scale on-demand streaming services. It is based on a special H/W device, called Network-Storage card (NS card), which aims at accelerating streaming operation by shortening the data path from storage device to network interface. The design objective of EXT3NS is to minimize the delay and the delay variance of I/O request in the sequential workload on NS card. Metadata structure, file organization, metadata structure, unit of storage, etc. are elaborately tailored to achieve this objective. Further, EXT3NS provides the standard APIs to read and write files in storage unit of NS card. The streaming server utilizes it to gain high disk I/O bandwidth, to avoid unnecessary memory copies on the data path from disk to network, and to alleviates CPUs burden by offloading parts of network protocol processing, The EXT3NS is a full functional file system based on the popular EXT3. The performance measurements on our prototype video server show obvious performance improvements. Specifically, we obtain better results from file system benchmark program, and obtain performance improvements in disk read and network transmission, which leads to overall streaming performance increase. Especially, the streaming server shows much less servers CPU utilization and less fluctuation of client bit rate, hence more reliable streaming service is possible.

The new approach for inter-communication between guest domains on Virtual Machine Monitor

In general, the speed of internal communication on a single-machine is faster than the other communication.(e.g. communication between remote PCs through the local network) Therefore, we expected that the internal communication between guest domains on a single-machine of virtual machine monitor (VMM)[1] was also fast. However, in the experiment, it showed that rather the speed was slower than the other communication because each guest domain was not well considered to be executed on VMM. In other words, the guest domain has some problems in the architecture of communication and data transmission on VMM. In this paper, we find the causes of those problems and suggest a new design for internal communication to improve its performance. It is well considered to be executed on VMM and shows the performance improvement of bandwidth up to 8 times in comparison with existing internal communication. And it also reduced the latency to 25%.

Fast Operating System Switcher for mobile CE devices

This paper proposes a fast Operating System (OS) Switcher for ARM-based Consumer Electronics (CE) such as Smart Phones, Tablets and IPTVs. The OS switcher enables users to utilize multiple OSes on single H/W device without security problem from interference among OSes. The OS switcher is notably faster than the multi-boot approach and can preserve the previous working states. The OS switcher does not burden any run time overhead compared to virtualization and can be easily applied to the new product. We implemented the OS switcher in the bootloader layer without any modification of OS.

Design and implementation of kernel S/W for TCP/IP offload engine(TOE)

TCP/IP is the most commonly used protocol to communicate between servers, and is used in a wide range of applications. Unfortunately, TCP/IP places a very heavy burden on host CPUs. Server CPUs have begun to choke while processing the TCP/IP overhead associated with transferring data. We have known that the CPU power in todays servers is just sufficient to handle the TCP processing, leaving no CPU cycles for application processing. So, in this paper, to resolve upper problem, we present the design of kernel software for TCP/IP off-loading engine. In this paper, we define the design concept of TOE module, and describe its architecture, main functions and interfaces with TOE device. TOE module consists of three software layers, that is, TOE device driver, TOE offload protocol layer, TOE socket switching layer. TOE device and TOE kernel software have several advantages as below. First, it improves network and application performance, that is, increases network throughput and lowers client response time. Second, it extends the life of existing servers, that is, enabling existing servers to manage additional client loads and enables existing servers to respond more quickly to client queries

CORSET: Service-Oriented Resource Management System in Linux

Generally, system resources are not enough for many running services and applications in a system. And services are more important than single process in real world and they have different priority or importance. So each service should be treated with discrimination in aspect of system resources. But administrator can’t guarantee the specific service has proper resources in unsettled workload situation because many processes are in race condition. So, we suppose the service-oriented resource management subsystem to resolve upper problems. It guarantees the performance or QoS of the specific service in changeable workload situation by satisfying the minimum resource requirement for the service.