Green Cluster of Low-Power Embedded Hardware Server Accelerators
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GREEN CLUSTER OF LOW-POWER EMBEDDED HARDWARE SERVER ACCELERATORS NAVID MOHAGHEGH A DISSERTATION SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF APPLIED SCIENCE AND ENGINEERING GRADUATE PROGRAM IN COMPUTER SCIENCE AND ENGINEERING YORK UNIVERSITY, TORONTO, ONTARIO NOVEMBER 2011 Library and Archives Bibliotheque et Canada Archives Canada Published Heritage Direction du 1+1 Branch Patrimoine de I'edition 395 Wellington Street 395, rue Wellington Ottawa ON K1A0N4 Ottawa ON K1A 0N4 Canada Canada Your file Votre reference ISBN: 978-0-494-88639-7 Our file Notre reference ISBN: 978-0-494-88639-7 NOTICE: AVIS: The author has granted a non L'auteur a accorde une licence non exclusive exclusive license allowing Library and permettant a la Bibliotheque et Archives Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par telecommunication ou par I'lnternet, preter, telecommunication or on the Internet, distribuer et vendre des theses partout dans le loan, distrbute and sell theses monde, a des fins commerciales ou autres, sur worldwide, for commercial or non support microforme, papier, electronique et/ou commercial purposes, in microform, autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriete du droit d'auteur ownership and moral rights in this et des droits moraux qui protege cette these. Ni thesis. Neither the thesis nor la these ni des extraits substantiels de celle-ci substantial extracts from it may be ne doivent etre imprimes ou autrement printed or otherwise reproduced reproduits sans son autorisation. without the author's permission. In compliance with the Canadian Conformement a la loi canadienne sur la Privacy Act some supporting forms protection de la vie privee, quelques may have been removed from this formulaires secondaires ont ete enleves de thesis. cette these. While these forms may be included Bien que ces formulaires aient inclus dans in the document page count, their la pagination, il n'y aura aucun contenu removal does not represent any loss manquant. of content from the thesis. Canada IV Abstract Power consumption is the largest operating expense in any server farm. In this thesis, we provide a cluster of low cost and low-power embedded hardware accelerators that can perform simple application level serving tasks (e.g. dynamic and static web hosting). The cluster can either replace powerful servers or can be used as extra torque for peak traffic moments. The cluster can boot in less than 10 seconds allowing rapid deployment into the network. The cluster will just provide enough acceleration to pass the service level agreement (SLA) on peak traffic moments in contrast to bringing a powerful server to the network , which may be overkill solution for the surge of traffic. We also propose a new technique for admission control in order to enforce the SLA by dropping selective requests instead of overloading the entire system and slowing down every body. Simulation using Matlab shows that our proposed scheme outperforms previously known admission control policies in the case of M/G/l system assumption (e.g. a general memoryless stochastic system). We also implement our system using micro-controller boards as accelerator and Linux as the operating system. We intensively tested out proposed system in order to compare it with the state of the art powerful servers. Real traffic is generated for the testing of the cluster. The result is that a tiny accelerator by itself is slower than a powerful server (7-11 times slower). However it only consumes about 1-2% of the energy used by powerful Internet servers. If the objective is not minimizing the time of serving a request but rather increasing the throughput and maintaining the required SLA, a cluster of embedded controllers could be used in order to handle the same amount of traffic as a powerful state of the art Internet server. The proposed accelerator cluster is using 8 times lower energy in comparison to a powerful server while handling the same amount of traffic and producing response times that are only 7 toll times slower. Adaptive admission-based controls are also implemented to provide SLA grantee on quality of service (QoS) of the cluster. VI Table of Contents 1: Introduction ............................................................................................................................ 1 2: Previous W o rk .......................................................................................................................4 2.1 Current State Of The Market ..........................................................................................4 2.1.1 Hard Disk Drive Improvements ............................................................................ 4 2.1.2 Attempts To Make More Efficient Power Supplies ............................................5 2.1.3 More Cores Per C P U ............................................................................................. 6 2.1.4 Extensive Use of Virtual Machines .......................................................................7 2.1.5 Using Faster CPUs..................................................................................................9 2.1.6 Prefetching and Service Differentiation ............................................................... 9 2.1.7 Using RAM for Random Access Data Intensive Operations ...........................10 2.1.8 Sleep Modes Instead of Complete Shutdown ................................................... 10 2.1.9 Dynamic Voltage Scaling.................................................................................... 11 2.1.10 Dynamic Acceptance Rate on Peak Traffic Hours ..........................................11 2.2 Related Work ..................................................................................................................13 2.3 Using Embedded Devices as Server Accelerators .................................................... 16 3: Admission Controlled Environment ...............................................................................18 3.1 Using Admission Control............................................................................................18 3.1.1 Using PI Controller ...............................................................................................20 3.1.2 Estimating the System Parameters......................................................................21 VII 3.1.3 Additive Increase Multiplicative Decrease ......................................................... 23 3.2 Simulations ....................................................................................................................24 4: Proposed System Architecture ......................................................................................... 31 4.1 System Reference Architecture .................................................................................. 31 4.2 Utilized Software and Protocols ..................................................................................32 4.2.1 Linux Kernel and M odules ................................................................................. 33 4.2.2 File system, Hard Disk Drives and RAID Topology ....................................... 34 4.2.3 TFTP, PXE, NFS...................................................................................................35 4.2.4 U-BOOT, INITRD, BusyBox ..............................................................................37 4.2.5 LVS and Routing ...................................................................................................38 4.2.6 FastCGI, SNMP, Cherokee and PHP ..................................................................44 4.3 Admission Control and Load-Balancing .................................................................... 46 4.4 Detail View of the Proposed Accelerator Cluster ...................................................... 48 4.5 Power Consumption .................................................................................................... 51 5: Testing and Results ............................................................................................................ 56 5.1 SpecWeb2009................................................................................................................59 5.2 Apache AB Benchmarker ............................................................................................60 5.3 Custom Made Benchmarker ........................................................................................ 63 5.4 Effectiveness of Admission control ............................................................................ 65 6: Conclusion ...........................................................................................................................68 7: Future Work ........... ................................................70 8: References CH.l: INTRODUCTION The use of the Internet is spreading into every comer of our lives from banking and shopping to distributed databases used in large corporations [1]. A special group of machines, known as servers, are used to host Internet applications. Unfortunately, most of these servers aggressively consume electricity due to their fast speed and broad capabilities. Power consumption is the largest operating expense in any server