AIX Versions 3.2 and 4 Performance Tuning Guide

<BODY BGCOLOR="FCFBF0"> <CENTER> <FONT COLOR="#A62A2A" SIZE="+2"> </FONT> </CENTER> <HR> <H1><A HREF="edition.htm#A3C10D3F823mhay">Fifth Edition (April 1996) </A></H1> <H1><A HREF="trademarks.htm#A2416DAE909bren">Trademarks and Acknowledgements</A></H1> <H1><A HREF="about.htm#D2B270A516wate">About This Book </A></H1> <H1><A HREF="concepts.htm#C0135C8182joy">Chapter 1. Performance Concepts</A></H1> <H2><A HREF="perftuning.htm#C0135CE952joy">An Introduction to the Performance-Tuning Process</A></H2> <H2><A HREF="benchmark.htm#DVrmm230mela">Performance Benchmarking-the Inevitable Dirtiness of Performance Data</A></H2> <H1><A HREF="resrcmanovr.htm#Q2D2i380doug">Chapter 2. AIX Resource Management Overview</A></H1> <H2><A HREF="schedov.htm#A5Jgmi1fcwate">Performance Overview of the AIX CPU Scheduler</A></H2> <H2><A HREF="vmmov.htm#C0135A5557joy">Performance Overview of the Virtual Memory Manager (VMM)</A></H2> <H2><A HREF="fdiskman.htm#C0135AA659joy">Performance Overview of AIX Management of Fixed-Disk Storage</A></H2> <H1><A HREF="multiprocintro.htm#fHumm3fmela">Chapter 3. An Introduction to Multiprocessing</A></H1> <H2><A HREF="smpcon.htm#a9vrj70wate">Symmetrical Multiprocessor (SMP) Concepts and Architecture</A></H2> <H2><A HREF="smpperfi.htm#cKumm2d9mela">SMP Performance Issues</A></H2> <H2><A HREF="smpenviron.htm#KLumm171mela">Adapting Programs to an SMP Environment</A></H2> <H2><A HREF="smpworkload.htm#cSumm171mela">SMP Workloads</A></H2> <H2><A HREF="smpsched.htm#ISummb8mela">SMP Scheduling</A></H2> <H2><A HREF="procaffin.htm#PWVxj1e9wate">Processor Affinity and Binding</A></H2> <H1><A HREF="perfplan.htm#D2B27E7505wate">Chapter 4. Performance-Conscious Planning, Design, and Implementation</A></H1> <H2><A HREF="desnimpl.htm#cfl8j390wate">Design and Implementation of Efficient Programs</A></H2> <H2><A HREF="perfinst.htm#Igl8j14fwate">Performance-Related Installation Guidelines</A></H2> <H1><A HREF="sysmonitor.htm#D2B2818163wate">Chapter 5. System Monitoring and Initial Performance Diagnosis </A></H1> <H2><A HREF="contperfmon.htm#Z3m8j158wate">The Case for Continuous Performance Monitoring</A></H2> <H2><A HREF="perfmonu.htm#A74m8j2c7wate">Performance Monitoring Using iostat, netstat, vmstat</A></H2> <H1><A HREF="monntuncpu.htm#A5J98j33awate">Chapter 6. Monitoring and Tuning CPU Use</A></H1> <H2><A HREF="vmstatcpu.htm#HjDAi32bwate">Using vmstat to Monitor CPU Use</A></H2> <H2><A HREF="measurcpu.htm#w983jebwate">Using the time Command to Measure CPU Use</A></H2> <H2><A HREF="monitorcpu.htm#D2B2840812wate">Using xmperf to Monitor CPU Use</A></H2> <H2><A HREF="cpuintensive.htm#M5B3j3c1wate">Using ps to Identify CPU-Intensive Programs</A></H2> <H2><A HREF="tprof4cpu.htm#C01353B875joy">Using tprof to Analyze Programs for CPU Use</A></H2> <H2><A HREF="cntrlflwanal.htm#A6B3j1e1wate">Detailed Control Flow Analysis with stem</A></H2> <H2><A HREF="execfdpr.htm#pDWVj347wate">Restructuring Executables with fdpr</A></H2> <H2><A HREF="contend4cpu.htm#pw98j20fwate">Controlling Contention for the CPU</A></H2> <H2><A HREF="schedtimeslice.htm#aNY1j3e3wate">Modifying the Scheduler Time Slice</A></H2> <H2><A HREF="idadmin.htm#bf5Bjbbwate">CPU-Efficient User ID Administration</A></H2> <H1><A HREF="tuningmem.htm#eAD2i2ddoug">Chapter 7. Monitoring and Tuning Memory Use</A></H1> <H2><A HREF="memoryuse.htm#HhY1j39wate">How Much Memory Is Really Being Used?</A></H2> <H2><A HREF="membigfoot.htm#xFPAj2d9wate">Analyzing Patterns of Memory Use with BigFoot</A></H2> <H2><A HREF="memrmss.htm#C01364F517joy">Assessing Memory Requirements via the rmss Command</A></H2> <H2><A HREF="vmmmemld.htm#C013656993joy">Tuning VMM Memory Load Control</A></H2> <H2><A HREF="vmmpage.htm#A3rA1j8wate">Tuning VMM Page Replacement</A></H2> <H1><A HREF="montundisk.htm#UPD2i2f9doug">Chapter 8. Monitoring and Tuning Disk I/O</A></H1> <H2><A HREF="seqread.htm#DGV8j3bewate">Tuning Sequential Read Ahead</A></H2> <H2><A HREF="diskpace.htm#C013657651joy">Use of Disk-I/O Pacing</A></H2> <H2><A HREF="lvstrip.htm#D2B2891435wate">Logical Volume Striping</A></H2> <H2><A HREF="fragsize.htm#D2B2891675wate">File-System Fragment Size</A></H2> <H2><A HREF="compress.htm#A4lJIj264wate">Compression</A></H2> <H2><A HREF="asyncio.htm#olJIj343wate">Asynchronous Disk I/O</A></H2> <H2><A HREF="diskio.htm#D2B2892170wate">Using Raw Disk I/O</A></H2> <H2><A HREF="syncfsync.htm#D2B2892761wate">Using Performance Implications of sync/fsync</A></H2> <H2><A HREF="scsiparms.htm#KdZRj37cwate">Modifying the SCSI Device Driver max_coalesce Parameter</A></H2> <H2><A HREF="scsiqueue.htm#SguOj98wate">Setting SCSI-Adapter and Disk-Device Queue Limits</A></H2> <H2><A HREF="syspbufs.htm#oA2fj1fbwate">Controlling the Number of System pbufs</A></H2> <H1><A HREF="montuncomm.htm#CD90F2F237wate">Chapter 9. Monitoring and Tuning Communications I/O</A></H1> <H2><A HREF="udptcpperfov.htm#CD90F2F335wate">UDP/TCP/IP Performance Overview</A></H2> <H2><A HREF="tcpudpperftun.htm#CD90F2F384wate">TCP and UDP Performance Tuning</A></H2> <H2><A HREF="mbufperftun.htm#L1TAj35ewate">mbuf Pool Performance Tuning</A></H2> <H2><A HREF="mbuftunparms.htm#CD90F30183wate">UDP, TCP/IP, and mbuf Tuning Parameters Summary</A></H2> <H2><A HREF="nfstuning.htm#CD90F31996wate">NFS Tuning</A></H2> <H2><A HREF="diskless.htm#CD90F35101wate">Serving Diskless Workstations</A></H2> <H2><A HREF="asynctuning.htm#C013658783joy">Tuning Asynchronous Connections for High-Speed Transfers</A></H2> <H2><A HREF="netpmoneval.htm#wj5Dj27bwate">Using netpmon to Evaluate Network Performance</A></H2> <H2><A HREF="iptraceanal.htm#n2TAj95wate">Using iptrace to Analyze Performance Problems</A></H2> <H1><A HREF="dfsperftun.htm#D2B2919340wate">Chapter 10. DFS Performance Tuning </A></H1> <H2><A HREF="dfsperftun.htm#hsODja5wate">DFS Caching on Disk or Memory?</A></H2> <H2><A HREF="dfsperftun.htm#M4SDja3wate">DFS Cache Size</A></H2> <H2><A HREF="dfsperftun.htm#JsODj3e5wate">DFS Cache Chunk Size</A></H2> <H2><A HREF="dfsperftun.htm#A1sODj8bwate">Number of DFS Cache Chunks</A></H2> <H2><A HREF="dfsperftun.htm#drODj1cfwate">Location of DFS Disk Cache</A></H2> <H2><A HREF="dfsperftun.htm#DrODj1fcwate">Cache Status-Buffer Size</A></H2> <H2><A HREF="dfsperftun.htm#OqODj219wate">Effect of Application Read/Write Size</A></H2> <H2><A HREF="dfsperftun.htm#sqODj217wate">Communications Parameter Settings for DFS</A></H2> <H2><A HREF="dfsperftun.htm#ZRkcj220wate">DFS File Server Tuning</A></H2> <H2><A HREF="dfsperftun.htm#wRkcj10cwate">DCE LFS Tuning for DFS Performance</A></H2> <H1><A HREF="tracefacil.htm#C013834277joy">Chapter 11. Performance Analysis with the Trace Facility</A></H1> <H2><A HREF="tracefacunder.htm#cGGVi357cand">Understanding the Trace Facility</A></H2> <H2><A HREF="tracefacexp.htm#D2B2930240wate">An Example of Trace Facility Use</A></H2> <H2><A HREF="strtstptrace.htm#C013835082joy">Starting and Controlling Trace from the Command Line</A></H2> <H2><A HREF="conttracprog.htm#D2B2933491wate">Starting and Controlling Trace from a Program</A></H2> <H2><A HREF="addtraceevent.htm#C013837884joy">Adding New Trace Events</A></H2> <H1><A HREF="perfdiagtool.htm#CviJj2wate">Chapter 12. Performance Diagnostic Tool (PDT)</A></H1> <H2><A HREF="perftoolbox.htm#D2B281B307wate">The AIX Performance Toolbox</A></H2> <H2><A HREF="perfprobrep.htm#F6m8j41wate">Inference from the Kind of Performance Problem Reported</A></H2> <H2><A HREF="useperfdiag.htm#x6m8j56wate">Using PerfPMR for Performance Diagnosis</A></H2> <H2><A HREF="idperfres.htm#C013538071joy">Identifying the Performance-Limiting Resource</A></H2> <H2><A HREF="workloadman.htm#D8m8j2ebwate">Workload Management</A></H2> <H1><A HREF="aixperfbug.htm#eU68j370wate">Chapter 13. Handling a Possible AIX Performance Bug</A></H1> <H2><A HREF="aixperfbug.htm#D2B2944382wate">Measuring the Baseline</A></H2> <H2><A HREF="aixperfbug.htm#D2B2944512wate">Reporting the Problem</A></H2> <H2><A HREF="aixperfbug.htm#D2B2948980wate">Obtaining and Installing AIX Version 3.2.5 PerfPMR</A></H2> <H2><A HREF="aixperfbug.htm#Swsjls">Installing PerfPMR from the Web (includes Version 4)</A></H2> <H2><A HREF="aixperfbug.htm#D2B2946187wate">Problem-Analysis Data</A></H2> <H1><A HREF="perfmontuncmds.htm#A9DC8i25edoug">Appendix A. AIX Performance Monitoring and Tuning Commands</A></H1> <H2><A HREF="emstat.htm#A312emstatbkg">emstat Command</A></H2> <H2><A HREF="schedtune.htm#C01381E198joy">schedtune Command</A></H2> <H2><A HREF="vmtune.htm#hDEci3c8cand">vmtune Command</A></H2> <H2><A HREF="pdt_config.htm#p8MJj252wate">pdt_config Script</A></H2> <H2><A HREF="pdt_report.htm#X9MJj3d3wate">pdt_report Script</A></H2> <H1><A HREF="perfsubs.htm#I6SGi259doug">Appendix B. Performance-Related Subroutines</A></H1> <H1><A HREF="cacheaddr.htm#C013792712joy">Appendix C. Cache and Addressing Considerations</A></H1> <H2><A HREF="cacheaddr.htm#A1B836A2454bren">Disclaimer</A></H2> <H2><A HREF="cacheaddr.htm#A1B836A2844bren">Addressing</A></H2> <H2><A HREF="cacheaddr.htm#A1B836A3423bren">Cache Lookup</A></H2> <H2><A HREF="cacheaddr.htm#C013794091joy">TLB Lookup</A></H2> <H2><A HREF="cacheaddr.htm#A1B836A5357bren">RAM Access</A></H2> <H2><A HREF="cacheaddr.htm#A1B836A5944bren">Implications</A></H2> <H1><A HREF="useldcmd.htm#C013619081joy">Appendix D. Efficient Use of the ld Command</A></H1> <H2><A HREF="useldcmd.htm#C013619328joy">Rebindable Executables</A></H2> <H2><A HREF="useldcmd.htm#C013619664joy">Prebound Subroutine Libraries</A></H2> <H2><A HREF="useldcmd.htm#C013619993joy">Examples</A></H2> <H2><A HREF="useldcmd.htm#D2B29CB797wate">Related Information</A></H2> <H1><A HREF="perftoolsperf.htm#NXV8j377wate">Appendix E. Performance of the Performance Tools</A></H1> <H1><A HREF="memmanage.htm#C013609938joy">Appendix F. Application Memory Management-malloc and realloc</A></H1> <H1><A HREF="perfsharedlibs.htm#C0135FD988joy">Appendix G. Performance Effects of Shared Libraries</A></H1> <H2><A HREF="perfsharedlibs.htm#C0135FE229joy">Advantages and Disadvantages of Shared Libraries</A></H2> <H2><A HREF="perfsharedlibs.htm#C0135FE494joy">How to Build Executables Shared or Nonshared</A></H2> <H2><A HREF="perfsharedlibs.htm#C0135FE743joy">How to Determine If Nonshared Will Help</A></H2> <H2><A HREF="perfsharedlibs.htm#D2B29EB597wate">Related Information</A></H2> <H1><A HREF="accproctimer.htm#C013759361joy">Appendix H. Accessing the Processor Timer</A></H1> <H2><A HREF="accproctimer.htm#D2B29F9646wate">POWER-Architecture-Unique Timer Access</A></H2> <H2><A HREF="accproctimer.htm#D2B29FA013wate">Accessing Timer Registers in PowerPC-Architecture Systems</A></H2> <H2><A HREF="accproctimer.htm#C01375A152joy">Example Use of the second Routine</A></H2> <H1><A HREF="natlangsup.htm#RSr8j1a4wate">Appendix I. National Language Support-Locale vs Speed</A></H1> <H2><A HREF="natlangsup.htm#D2B2A05074wate">Programming Considerations</A></H2> <H2><A HREF="natlangsup.htm#D2B2A05299wate">Some Simplifying Rules</A></H2> <H2><A HREF="natlangsup.htm#D2B2A06082wate">Controlling Locale</A></H2> <H2><A HREF="natlangsup.htm#D2B2A06537wate">Related Information</A></H2> <H1><A HREF="tunableaixparms.htm#D2B2A1E557wate">Appendix J. Summary of Tunable AIX Parameters</A></H1> <H2><A HREF="tunableaixparms.htm#DEB526D170wate">arpt_killc</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526D553wate">biod Count</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526D955wate">Disk Adapter Outstanding-Requests Limit</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526E351wate">Disk Drive Queue Depth</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526E746wate">dog_ticks</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526F110wate">fork() Retry Interval</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526F510wate">ipforwarding</A></H2> <H2><A HREF="tunableaixparms.htm#DEB526F889wate">ipfragttl</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5270269wate">ipqmaxlen</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5270653wate">ipsendredirects</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5271035wate">loop_check_sum (AIX Version 3.2.5 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5271418wate">lowclust (AIX Version 3.2.5 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5271816wate">lowmbuf (AIX Version 3.2.5 only)</A></H2> <H2><A HREF="tunableaixparms.htm#A3C11A91386mhay">lvm_bufcnt (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#A3C11A91682mhay">maxrandwrt (AIX Version 4.1.3 and above)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5272209wate">maxbuf</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5272580wate">max_coalesce</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5272957wate">maxfree</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5273359wate">maxperm</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5273742wate">maxpgahead</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5274120wate">maxpin (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5274506wate">maxpout</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5274896wate">maxttl</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5275267wate">mb_cl_hiwat (AIX Version 3.2.5 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5275674wate">Memory-Load-Control Parameters</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5276122wate">minfree</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5276513wate">minperm</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5276890wate">minpgahead</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5277274wate">minpout</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5277662wate">MTU</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5278049wate">nfs_chars (AIX Version 3.2.5), nfs_socketsize (AIX Version 4)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5278435wate">nfsd Count</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5278820wate">nfs_gather_threshold (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5279191wate">nfs_portmon (AIX Version 3.2.5), portcheck (AIX Version 4)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5279565wate">nfs_repeat_messages (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5279934wate">nfs_setattr_error (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527A299wate">nfsudpcksum (AIX Version 3.2.5), udpchecksum (AIX Version 4)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527A670wate">nonlocsrcroute</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527B041wate">npskill (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527B415wate">npswarn (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527B792wate">numclust (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527C164wate">numfsbuf (AIX Version 4 only)</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527C546wate">Paging Space Size</A></H2> <H2><A HREF="tunableaixparms.htm#A3C11A92540mhay">pd_npages </A></H2> <H2><A HREF="tunableaixparms.htm#DEB527C936wate">Process-Priority Calculation</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527D326wate">rec_que_size</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527D701wate">rfc1122addrchk</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527E065wate">rfc1323</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527F471wate">sb_max</A></H2> <H2><A HREF="tunableaixparms.htm#DEB527F846wate">subnetsarelocal</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5280219wate">syncd Interval</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5280589wate">tcp_keepidle</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5280960wate">tcp_keepintvl</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5281332wate">tcp_mssdflt</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5281699wate">tcp_recvspace</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5282079wate">tcp_sendspace</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5282456wate">tcp_ttl</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5282824wate">thewall</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5283203wate">Time-Slice Expansion Amount</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5283570wate">udp_recvspace</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5283949wate">udp_sendspace</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5284324wate">udp_ttl</A></H2> <H2><A HREF="tunableaixparms.htm#DEB5284685wate">xmt_que_size</A></H2>