IBM pSeries manual Introduction

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1.0 Introduction

This paper is intended to help you tune and debug the performance of the IBM ®

pSeries® High Performance Switch (HPS) on IBM Cluster 1600 systems. It is not~intended to be

a comprehensive guide, but rather to help in initial tuning and debugging of performance issues. Additional detailed information on the materials presented here can be found in sources noted in the text and listed in section 7.0.

This paper assumes an understanding of MPI and AIX 5L™, and that you are familiar with and have access to the Hardware Management Console (HMC) for pSeries systems.

This paper is divided into four sections. The first deals with HPS-specific tunables for tuning the HPS subsystems. The second section deals with tuning AIX 5L and its components for optimal performance of the HPS system. The third section deals with tuning various system daemons in both AIX 5L and cluster environments to prevent impact on high-performance parallel applications. The final section deals with debugging performance problems on the HPS.

Before debugging a performance problem in the HPS, review the HPS and AIX 5L tuning as well as daemon controls. Many problems are specifically related to these subsystems. If a performance problem persists after you follow the instructions in the debugging section, call IBM service for additional tools and help.

We want to thank the following people in the IBM Poughkeepsie development organization for their help in writing this paper:

Robert Blackmore

George Chochia

Frank Johnston

Bernard King-Smith

John Lewars

Steve Martin

Fernando Pizzano

Bill Tuel

Richard Treumann

pshpstuningguidewp040105.doc

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Contents IBM ~pSeries High Performance Switch Contents Mpprintenv Mpstatistics Introduction Tunables and settings for switch software MPI tunables for Parallel EnvironmentMpeagerlimit MppollingintervalMprexmitbufsize and Mprexmitbufcnt MemoryaffinityMpcssinterrupt MptaskaffinityMPI-IO Chgsni command IP tunables Tunables and settings for AIX 5LFile cache Svmon and vmstat commands Svmon Vsid Esid Type Description LPage Inuse Pin Pgsp VirtualVmstat Pin Pgsp VirtualLarge page sizing Pshpstuningguidewp040105.doc Memory affinity for a single Lpar Large pages and IP supportAmount of memory available Daemon configuration Debug settings in the AIX 5L kernelRsct daemons Reducing the number of daemons running LoadLeveler daemonsReducing logging Placement of POE managers and LoadLeveler scheduler Settings for AIX 5L threadsAIX 5L mail, spool, and sync daemons Debug settings and data collection tools Lsattr tuningDriverdebug setting Iptrclvl settingSmall Real Mode Address Region on HMC GUI Deconfigured L3 cacheService focal point Affinity LPARsHMC error logging Errpt commandMultiple versions of MPI libraries Mpprintenv Mpstatistics MemoryaffinityDropped switch packets Nddipacketsmsw 0x00000000 Nddipacketslsw Packets dropped in the ML0 interface Packets dropped because of a hardware problem on an endpoint Packets dropped in the switch hardware MpinfolevelLapidebugcommtimeout LapidebugperfAIX 5L trace for daemon activity Conclusions and summaryAdditional reading HPS documentationPOWER4 MPI documentationAIX 5L performance guides IBM RedbooksPshpstuningguidewp040105.doc
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