The Evolution of the Linux Build System

Software evolution entails more than just redesigning and reimplementing functionality of, fixing bugs in, or adding new features to source code. These evolutionary forces induce similar changes on the software's build system too, with far-reaching consequences on both overall developer productivity as well as software configurability. In this paper we take a look at this phenomenon in the Linux kernel from its inception up until present day. We do this by analysing the kernel's build traces with MAKAO, our re(verse)-engineering framework for build systems. This helps us in detecting interesting idioms and patterns in the dynamic build behaviour. Finding a good balance between obtaining a fast, correct build system and migrating in a stepwise fashion turns out to be the general theme throughout the evolution of the Linux build system

Bug Fix Time Optimization Using Matrix Factorization and Iterative Gale-Shaply Algorithms

Bug triage is an essential task in software maintenance phase. It assigns developers (fixers) to bug reports to fix them. This process is performed manually by a triager, who analyzes developers profiles and submitted bug reports to make suitable assignments. Bug triaging process is time consuming thus automating this process is essential to improve the quality of software. Previous work addressed triaging problem either as an information retrieval or classification problem. This paper tackles this problem as a resource allocation problem, that aims at the best assignments of developers to bug reports, that reduces the total fixing time of the newly submitted bug reports, in addition to the even distribution of bug reports over developers. In this paper, a combination of matrix factorization and Gale Shapely algorithm, supported by the differential evolution is firstly introduced to optimize the total fix time and normalize developers work load. Matrix factorization is used to establish a recommendation system for Gale-Shapley to make assignment decisions. Differential evolution provides the best set of weights to build developers score profiles. The proposed approach is assessed over three repositories, Linux, Apache and Eclipse. Experimental results show that the proposed approach reduces the bug fixing time, in comparison to the manual triage, by 80.67%, 23.61% and 60.22% over Linux, Eclipse and Apache respectively. Moreover, the workload for the developers is uniform.Comment: 14 page, 7 figures, 8 tables, 10 equation

Unikernels: the next stage of Linux’s dominance

Unikernels have demonstrated enormous advantages over Linux in many important domains, causing some to propose that the days of Linux's dominance may be coming to an end. On the contrary, we believe that unikernels' advantages represent the next natural evolution for Linux, as it can adopt the best ideas from the unikernel approach and, along with its battle-tested codebase and large open source community, continue to dominate. In this paper, we posit that an upstreamable unikernel target is achievable from the Linux kernel, and, through an early Linux unikernel prototype, demonstrate that some simple changes can bring dramatic performance advantages.Accepted manuscrip

Assessing Code Authorship: The Case of the Linux Kernel

Code authorship is a key information in large-scale open source systems. Among others, it allows maintainers to assess division of work and identify key collaborators. Interestingly, open-source communities lack guidelines on how to manage authorship. This could be mitigated by setting to build an empirical body of knowledge on how authorship-related measures evolve in successful open-source communities. Towards that direction, we perform a case study on the Linux kernel. Our results show that: (a) only a small portion of developers (26 %) makes significant contributions to the code base; (b) the distribution of the number of files per author is highly skewed --- a small group of top authors (3 %) is responsible for hundreds of files, while most authors (75 %) are responsible for at most 11 files; (c) most authors (62 %) have a specialist profile; (d) authors with a high number of co-authorship connections tend to collaborate with others with less connections.Comment: Accepted at 13th International Conference on Open Source Systems (OSS). 12 page

A Novel Approach to Multiagent based Scheduling for Multicore Architecture

In a Multicore architecture, eachpackage consists of large number of processors. Thisincrease in processor core brings new evolution inparallel computing. Besides enormous performanceenhancement, this multicore package injects lot ofchallenges and opportunities on the operating systemscheduling point of view. We know that multiagentsystem is concerned with the development andanalysis of optimization problems. The main objectiveof multiagent system is to invent some methodologiesthat make the developer to build complex systems thatcan be used to solve sophisticated problems. This isdifficult for an individual agent to solve. In this paperwe combine the AMAS theory of multiagent systemwith the scheduler of operating system to develop anew process scheduling algorithm for multicorearchitecture. This multiagent based schedulingalgorithm promises in minimizing the average waitingtime of the processes in the centralized queue and alsoreduces the task of the scheduler. We actuallymodified and simulated the linux 2.6.11 kernel processscheduler to incorporate the multiagent systemconcept. The comparison is made for different numberof cores with multiple combinations of process and theresults are shown for average waiting time Vs numberof cores in the centralized queue

Multistage Switching Architectures for Software Routers

Software routers based on personal computer (PC) architectures are becoming an important alternative to proprietary and expensive network devices. However, software routers suffer from many limitations of the PC architecture, including, among others, limited bus and central processing unit (CPU) bandwidth, high memory access latency, limited scalability in terms of number of network interface cards, and lack of resilience mechanisms. Multistage PC-based architectures can be an interesting alternative since they permit us to i) increase the performance of single software routers, ii) scale router size, iii) distribute packet manipulation and control functionality, iv) recover from single-component failures, and v) incrementally upgrade router performance. We propose a specific multistage architecture, exploiting PC-based routers as switching elements, to build a high-speed, largesize,scalable, and reliable software router. A small-scale prototype of the multistage router is currently up and running in our labs, and performance evaluation is under wa

Scalable Layer-2/Layer-3 Multistage Switching Architectures for Software Routers

Software routers are becoming an important alternative to proprietary and expensive network devices, because they exploit the economy of scale of the PC market and open-source software. When considering maximum performance in terms of throughput, PC-based routers suffer from limitations stemming from the single PC architecture, e.g., limited bus bandwidth, and high memory access latency. To overcome these limitations, in this paper we present a multistage architecture that combines a layer-2 load-balancer front-end and a layer-3 routing back-end, interconnected by standard Ethernet switches. Both the front-end and the back-end are implemented using standard PCs and open- source software. After describing the architecture, evaluation is performed on a lab test-bed, to show its scalability. While the proposed solution allows to increase performance of PC- based routers, it also allows to distribute packet manipulation functionalities, and to automatically recover from component failures

Towards maintainer script modernization in FOSS distributions

Free and Open Source Software (FOSS) distributions are complex software systems, made of thousands packages that evolve rapidly, independently, and without centralized coordination. During packages upgrades, corner case failures can be encountered and are hard to deal with, especially when they are due to misbehaving maintainer scripts: executable code snippets used to finalize package configuration. In this paper we report a software modernization experience, the process of representing existing legacy systems in terms of models, applied to FOSS distributions. We present a process to define meta-models that enable dealing with upgrade failures and help rolling back from them, taking into account maintainer scripts. The process has been applied to widely used FOSS distributions and we report about such experiences