1. Anne C. Elster1 CLUSTER TECHNOLOGIES (Foilene ble også presentert på NOTUR 2003) Anne C. Elster Dept. of Computer & Information Science (IDI) Norwegian Univ. of Science & Tech. (NTNU) Trondheim, Norway NFR 30. juni, 2003

2. Anne C. Elster2 Clusters (Networks of PCs/Workstation) Are they suitable for HPC? Advantage: Cost-effective hardware since uses COTS (Commercial Of-The-shelf) parts BUT: Typically much slower processor interconectes than traditional HPC systems What about usability? NTNU IDI’s 40-node AMD 1.46GHz cluster 2GB RAM, 40GB disk, Fast Ethernet

3. Anne C. Elster3 Cluster Technologies: NOTUR Emerging Technology project Collaboration between NTNU & Univ. of Tromsø Goal: Analyze Cluster technologies’ suitability for HPC by looking at some of the most interesting NOTUR applications The results will provide a foundation for decisions regarding future HPC programs

4. Anne C. Elster4 Main Collaborators include Anne C. Elster (IDI, NTNU) – Project leader Otto Anshus & Tore Larsen (CS, U of Tromsø Torbjørn Hallgren (IDI, NTNU) Einar Rønquist (IMF, NTNU) Master, Ph.D. Students & Post Docs at NTNU and Univ. of Tromsø

5. Anne C. Elster5 General Issues to Consider: Why cluster vs. Powerful desktop vs. Large SMPs? What are the total costs associated with clusters (harware, software, support, usability) 32-bit vs. 64-bit architectures

6. Anne C. Elster6 Cluster Project ACTIVITIES: Profiling & Tuning Selected Applications: –Physics and Chemistry Codes (Elster & students, Dept. of Computer Science Dept., NTNU) –Profiling & User-Analysis of Amber, Dalton & Gaussian (Tor Johansen & staff, Comp. Center, U of Tromsø) –Optimization & tool analysis of Dalton (Anshus & PostDoc/student, Dept. of Comp. Sci., U of Tromsø)

7. Anne C. Elster7 Cluster Project ACTIVITIES continuted: Execution Monotoring (Anshus, Tore Larsen & students, CS, U of T) Visualization servers, etc. (Hallgren, Elster & students, CS, NTNU) Impact of future numerical algorithms (Rønquist & student, Dept. of Mathematics, NTNU Interface with NOTUR ET – Grid Project (Elster, Harald Simonsen and colleagues, staff & students associated with the NOTUR ET Cluster & Grid projects)

8. Anne C. Elster8 Some cluster issues discovered: Performance of programs can individually vary on different machines FORTRAN problems: –Different FORTRAN implementations have non-stardard add-ons (e.g. FORTRAN 90) –Leads to great difficulty in porting code to a different platform with a different Fortran compiler (e.g. by a different vendor)

9. Anne C. Elster9 Some cluster issues discovered continued: Global operations have more severe impact on performance on clusters than traditional supercomputers since communication between processors take relatively more time of total execution time

10. Anne C. Elster10 The ”Ideal” Cluster -- Hardware High-bandwidth network Low-latency network Low Operating System overhead (tcp causes ”slow start”) Great floating-point performance (64-bit?)

11. Anne C. Elster11 The ”Ideal” Cluster -- Software Compiler that is: –Portable –Optimizing Do extra work to save communication Self tuning /Load ballanced Automatically choose best algorithm One-sided communication support? Optimized middleware

12. Anne C. Elster12 For more information: Poster session at NOTUR Cluster Project stand - several posters+ smoke simulation demo Poster by Torbjørn Vik et. al. Poster by Lars Ailo Bongo Email: elster@computer.org