Ramesh K. Karne

DOSC: dispersed operating system computing

Over the past decade the sheer size and complexity of traditional operating systems have prompted a wave of new approaches to help alleviate the services provided by these operating systems. The emergence of micro-kernels and a plethora of non-traditional operating system models, both geared toward reducing the role of the OS, attest to the promise of practical alternatives. The problem with these methods is that the three-tiered system of software, operating system, and hardware is still preserved. Even though the operating system might find some reprieve by having to handle less work there is a nascent notion being triggered by these alternative approaches that the operating system as an abstract entity is no longer a necessity. We propose a radical method of computing where we take this notion to the extreme and push the operating system into the software and hardware levels. By doing so, we create a decentralized operating system environment known as Dispersed Operating System Computing (DOSC). We outline how the Dispersed Operating System paradigm works, its benefits, and immediate practical applications in todays world.

How to run C++ applications on a bare PC?

Most of the computer applications today run on a given operating system environment. The application programs written in a programming language such as C++ are intertwined with operating system and environment to run on a given machine. Thus, a C++ program requires a processor such as an Intel Pentium and an operating system such as a Microsoft Windows. Why do we have to run applications in such a constrained environment? It may be because, that is how evolution of computing happened since the inception of personal computers in the 80s. In this paper, we describe details on how to run C++ applications on a bare machine. We provide some benefits of running applications on a bare machine without any operating system. We present some sample applications that are built to demonstrate the capability of running C++ applications on a bare machine. Finally, we describe our future research direction that may potentially offer a revolution in computing architecture and application development.

A comparison of VoIP performance on IPv6 and IPv4 networks

We compare VoIP performance on IPv6 and IPv4 LANs in the presence of varying levels of background UDP traffic. A conventional softphone is used to make calls and a bare PC (operating systemless) softphone is used as a control to determine the impact of system overhead. The performance measures are maximum and mean delta (the time between the arrival of voice packets), maximum and mean jitter, packet loss, MOS (Mean Opinion Score), and throughput. We also determine the relative frequency distribution for delta. It is found that mean values of delta for IPv4 and IPv6 are similar although maximum values are much higher than the mean and show more variability at higher levels of background traffic. The maximum jitter for IPv6 is slightly higher than for IPv4 but mean jitter values are approximately the same. On an overloaded 100 Mbps link, packet loss can reach close to 18% for IPv4 and 24% for IPv6, and the MOS degrades significantly. At moderate levels of background traffic, the IPv4/IPv6 throughput ratio is close to the ideal (theoretical) throughput ratio, but at high levels of background traffic, throughput for IPv6 declines slightly faster than for IPv4. In general, our results indicate that the difference in VoIP performance for IPv6 and IPv4 is negligible. Results for the bare PC softphone confirm that reducing system and application overhead lowers delta and jitter values regardless of the IP version.

A Peer-to-Peer Bare PC VoIP Application

PC computing is a novel approach to computing in which there is no operating system, and applications are provided with direct interfaces to the hardware. Bare PC systems are of particular interest for secure, reliable, and efficient peer-to-peer communication between users in view of their inherent simplicity. In this paper, we first provide a brief overview of bare PC computing and note their advantages for peer-to-peer communication. We then describe a peer-to-peer bare PC VoIP application, and present call quality measurements including packet loss, delay, jitter, and MOS (Mean Opinion Score) from several experiments conducted in our laboratory. The results indicate that call quality achieved with bare PC VoIP systems is better than that of operating system based softphones. They also show that a bare PC is able to sustain larger voice packet sizes with no observable degradation in call quality. I. INTRODUCTION An operating system manages resources and interfaces between the users and the hardware. However, critics claim that todays operating systems are often plagued by buggy code and device drivers making them insecure and unreliable [15]. New generations of operating systems promise to provide enhanced security.

An Evaluation of Secure Real-Time Transport Protocol (SRTP) Performance for VoIP

The Secure Real-Time Transport Protocol (SRTP) is an Internet standards-track security profile for RTP used to provide confidentiality, integrity and replay protection for RTP traffic. We study the performance of SRTP when it is used to secure VoIP conversations. Experiments are conducted using snom and Twinkle softphones running on Windows and Linux platforms respectively and a bare PC softphone running with no operating system installed to provide a baseline. Pre-defined SRTP transforms based on AES counter mode encryption with a 128-bit key and HMAC-SHA-1 with a 32-bit authentication tag, as well as 192 and 256-bit AES keys and an 80-bit authentication tag are tested. Measurement of internal processing times for each operation in the SRTP protocol indicates that authentication processing is more expensive than encryption regardless of key or tag size. A comparison of jitter and delta (packet interarrival time) for secured and unsecured VoIP traffic reveals that the addition of SRTP protection to VoIP traffic over RTP has a negligible effect on voice quality. VoIP throughput with SRTP is about 2% more than with RTP alone since the insignificant increase in delay is offset by the small increase in packet size.

The Design and Implementation of a Bare PC Email Server

This paper presents the architecture, design and implementation of an email server that runs on a bare PC without an operating system or hard-disk. In addition to providing standard services offered by conventional email servers, the bare PC email server incorporates several unique features leveraging the absence of an operating system. For example, it implements novel algorithms for optimal multi-tasking, provides streamlined processing of messages enabling highly efficient integration of the SMTP and POP3 servers, and minimizes traditional software and protocol overhead. Additionally, it eliminates process overhead due to an operating system, offers enhanced security since the server is not vulnerable to attacks that target operating system flaws, and has a smaller code size. The complete server can be booted from removable media such as a USB drive. The bare PC email server demonstrates the ability of a self-contained, self-executing, complex software application to directly control the underlying PC hardware.

Mini Web Server Clusters for HTTP Request Splitting

HTTP request splitting is a new concept where the TCP connection and data transfer phases are dynamically split between servers without using a central dispatcher or load balancer. Splitting is completely transparent to the client and provides security due to the inaccessibility and invisibility of the data servers. We study the performance of mini Web server clusters with request splitting. With partial delegation in which some requests are split, throughput is better, and response times are only marginally less than for an equivalent non-split system. For example with partial delegation, for a four-node cluster with a single connection server and three data servers serving 64 KB files, and for a three-node cluster with two connection servers and a single data server serving 4 KB files, the respective throughput improvements over non-split systems are 10% and 22%, with only a marginal increase in response time. In practice, the throughput improvement percentages will be higher and response time gaps will be lower since we ignore the overhead of a dispatcher or load balancer in non-split systems. Although these experiments used bare PC Web servers without an operating system/kernel for ease of implementation, splitting and clustering may also be implemented on conventional systems.

Splitting HTTP requests on two servers

Many techniques are commonly used to increase server availability or for distributing the load among a group of servers. We propose a technique for splitting a single HTTP request that allows a TCP connection to be dynamically split between two Web servers without using a central control. For example, one server can handle connection establishment and closing, while another handles the data transfer. This approach requires no client involvement since the existing connection with the initial server continues to be maintained, and the client is completely unaware of the splitting. We demonstrate the splitting concept in a LAN environment and provide related performance results that highlight several interesting features of splitting. The splitting was done using two bare PC servers with no operating system (OS) or kernel running in the machines. Splitting also works with clients located anywhere on the Internet, although servers have to be located on the same LAN. Our implementation and results indicate the feasibility of splitting TCP connections to transparently redistribute server load without client involvement.

The Performance of a Bare Machine Email Server

Bare machine applications run directly over the hardware without using an operating system or a hard disk. This paper studies the performance of a bare machine email server whose design and implementation is based on several novel architectural features with a view towards optimizing performance. The results are compared with those for the AxiGen and ShareMailPro email servers, and a lean Java-based email server prototype running on Windows whose application-level operation closely matches that of the bare machine email server. For 80,000 emails in a LAN environment, the bare Machine server processing time is approximately 2 times faster than a Java-based server, and 2.4 times faster than the AxiGen server. For 5,500 emails in a WAN environment, the bare machine server performed at least 1.8 times faster than the Java-based and ShareMailPro servers. The results indicate that the bare machine email server outperforms the conventional email servers in LAN and WAN environments, and demonstrate the capability of using bare machines to build high-performance email servers.

A Study of Bare PC Web Server Performance for Workloads with Dynamic and Static Content

Bare PC applications do not use an operating system or kernel. The bare PC architecture avoids buffer copying, minimizes interrupts, uses a single thread of execution for processing network packets, and incorporates novel scheduling to minimize CPU utilization. We design a bare PC Web server that can serve both dynamic and static content. Measurements of response time, connection time and throughput for workloads containing requests for dynamic and static content indicate that the server has better performance than the Apache and IIS Web servers. For example, the bare PC server has a maximum request rate that is twice that of the Apache and IIS servers when serving dynamic content for small dataset sizes. Furthermore, at capacity the CPU utilization of the bare PC server is 1/5th that of the other servers. The bare PC server can also sustain a higher maximum request rate for dynamic pages with a given request rate for static pages. The studies demonstrate that the performance of the bare PC server when serving dynamic content is limited only by the latency of the database server.