1. Communication and Information Systems Lab. Application-Level Differentiated Services for Web Servers 2000. 9. 26. Tue. KAIST Dept. EECS CISLAB 송지영 jysong@comis.kaist.ac.kr

2. Communication and Information Systems Lab. 목차 qIntroduction and case study qFinding the server bottleneck resource qDesigning application-level background processing qBackground processing evaluation qRelated work and future work qCritique

3. Communication and Information Systems Lab. Introduction and case study qCurrent web service model : best-effort service qDifferentiated service levels are needed : 1Background requests and responses - anticipatory caching 1Content-derived priorities - HTML frames and inline images 1Policy-derived priorities - payment

4. Communication and Information Systems Lab. Finding the server bottleneck resource qBottleneck resources : 1CPU, physical memory, disk - CPU utilization 1Network - network throughput qTest environment 1Server 300MHz Pentium-II PC with FreeBSD, 128MB memory 1Server load - webstone-1.1 1Network - 10Mb/s and 100Mb/s ethernet qResults

5. Communication and Information Systems Lab. Designing app-level background processing qTwo queues for foreeground and background requests qThree backgrounding mechanisms 1Limit resource usage of background processes 1Lower the process priority of the background processes 1Limits the transmission rate of background processes

6. Communication and Information Systems Lab. Background processing evaluation qDesign space 1Backgrounding algorithm : unmodified and 3 proposed mechanism 1Network : 10/100Mbps ethernet 1Foreground load : light(20% util.), heavy(80%) load 1For 10Mbps : network-bounded, 3(light load) and 5(high) clients 1For 100Mbps : CPU-bounded, 15 and 20 clients qResults 1Very simple, but works well 1Limiting the network sending rate performs best 1Makes traffic less bursty 1Effective in the CPU-case 1Only for server-side : not for requests

7. Communication and Information Systems Lab. Related work and future work qRelated work : applying diff-serv to another level or layer 1Application-level 1Kernel-level extensions : AQUA, OMEGA 1Network layer : RSVP or diff-serv qFuture work 1Extensions for multicast content-push services 1More realistic model of client behavior

8. Communication and Information Systems Lab. Critique qContributions 1Numerical results about server bottleneck 1Applying diff-serv to application-level process qWeakness 1Does the figures in the graphs have meaning? 1Where’re the results of background processes?

9. Communication and Information Systems Lab. Cisco 7200/7500 qQoS tools 1Classification : using IP headers Port-based - packets from particular T1 line Application - all HTTP traffic Specific IP address Particular destination 1Queuing and Scheduling, Congestion avoidance 1Policing and shaping 1Signaling :RSVP 1Link Efficiency mechanisms : RTP