Posts Tagged ‘paper’

Interaction Between the User and Kernel Space in Linux

Sonntag, Januar 21st, 2018

Seminar Paper June 2017, Interaction Between the User and Kernel Space in Linux, Kai Lüke

Abstract:

System calls based on context switches from user to kernel space are the established concept for interaction in operating systems. On top of them the Linux kernel offers various paradigms for communication and management of resources and tasks. The principles and basic workings of system calls, interrupts, virtual system calls, special purpose virtual filesystems, process signals, shared memory, pipes, Unix or IP sockets and other IPC methods like the POSIX or System V message queue and Netlink are are explained and related to each other in their differences. Because Linux is not a puristic project but home for many different concepts, only a mere overview is presented here with focus on system calls.

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Design of a Python-subset Compiler in Rust targeting ZPAQL

Mittwoch, Oktober 19th, 2016

B.Sc. Thesis, Computer Science Freie Universität Berlin, Kai Lüke

Abstract:

The compressed data container format ZPAQ embeds decompression algorithms as ZPAQL bytecode in the archive. This work contributes a Python-subset compiler written in Rust for the assembly language ZPAQL, discusses design decisions and improvements. On the way it explains ZPAQ and some theoretical and practical properties of context mixing compression by the example of compressing digits of π. As use cases for the compiler it shows a lossless compression algorithm for PNM image data, a LZ77 variant ported to Python from ZPAQL to measure compiler overhead and as most complex case an implementation of the Brotli algorithm. It aims to make the development of algorithms for ZPAQ more accessible and leverage the discussion whether the current specification limits the suitability of ZPAQ as an universal standard for compressed archives.

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Web Connectivity in Ghana – A survey

Samstag, Juli 11th, 2015

Abstract:

Starting from the research “Dissecting web latency in Ghana” of Zaki et al. the field of Internet connectivity in Ghana is explored and the different aspects like latency, DNS resolution times, complexity of web sites, caching and prefetching, TLS/SSL, TCP and cellular network performance, role of ISPs, Internet Exchange Points, are brought in relation. Measurement approaches and tailored solutions for areas with bad connectivity are listed. Possible ways of improvement are discussed.

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Categories and Subject Descriptors: C.2.6 [Internetworking]: Standards; C.4 [Performance of Systems]: Reliability, availability, and serviceability

Keywords: Developing Countries, Internet, Latency, Performance, TCP, Mobile, Cellular