1. © 2012 IBM Corporation IBM Power Systems IBM i Intro to Performance Principles Tim Rowe timmr@us.ibm.comtimmr@us.ibm.com

2. © 2012 IBM Corporation IBM Power Systems 2 What Effects Performance ( 影响性能的因素 ) User expectations ( 用户的预期 ) Hardware capabilities and configuration ( 硬件配置 ) Software ( 软件 ) Workload ( 工作负载 ) Network ( 网络 )

3. © 2012 IBM Corporation IBM Power Systems 3 How to Accomplish Performance Results ( 如何实现性能调整 )  Plan ( 计划 ) –Establish expectations –Understand existing workloads  Analyze ( 分析 ) –Performance principles –Regular review of expectations & collected data  Tools – find the correct tool for what you are evaluating ( 使用恰当的工具 ) –Green Screen –Workload Estimator –IBM Navigator –Systems Director –Performance Data Investigator –iDoctor  Others

4. © 2012 IBM Corporation IBM Power Systems 4 Performance Management （性能管理 ) Set Performance Objectives and Create a Baseline （设定性能指标 ) Collect Performance Data ( 收集性能数据 ) Real-time Monitoring ( 实时监控 ) Analyze Performance Data ( 分析性能数据 ) Tuning ( 调优 ) Historical Trending ( 趋势分析和判断 ) Capacity Planning ( 系统配置计划 )

5. © 2012 IBM Corporation IBM Power Systems 5 Performance metrics ( 性能指标 ) Throughput （吞吐量 ) is the number of client requests an application environment has serviced over a given time period. Response time( 响应时间 ) is the elapsed time it takes to service a particular client’s request. Load( 负载 ) is the amount of main storage, processor, I/O support, and so forth, needed to satisfy all client requests at a given time.

6. © 2012 IBM Corporation IBM Power Systems 6 Basic performance contributors ( 影响性能的因素 ) è Processor Speed è Memory è Other Workload è Hardware Configuration è Operating System Settings è Middleware è Application Design è Data and Resource Access è Bandwidth è Latency è Design

7. © 2012 IBM Corporation IBM Power Systems 7 CPU Frequency Trends So Why?

8. © 2012 IBM Corporation IBM Power Systems 8 CPU Technology Trends （ CPU 技术趋势 )  Transistors continue to get smaller, but not much faster. –Enables more cores per chip, but limited clock frequency increase  Power (watts) has become a limitation in many IT shops. –New system can not use more power than previous system –Limits clock frequency; will be roughly constant going forward  Improvements in executing more instructions in a core in parallel are hitting diminishing returns.  Improvement in single thread performance will be much smaller than historical trends.  These are industry wide trends.  Adding more cores per chip and threads per core for throughput.

9. © 2012 IBM Corporation IBM Power Systems 9 Clock Speed vs CPW ( 频率 vs. CPW)  Clock Speed – raw processing speed of a core –Does not factor in I/O –Waits –Scheduling  Power story – CPW (Commercial Processing Workload) –Measure of how much ‘work’ can be done by a core –Factors in CPU Frequency, I/O access, Disk Access, task scheduling Frequency has always been a component of this capacity, but frequency never was the only means of improving capacity.

10. © 2012 IBM Corporation IBM Power Systems 10 Basics of Performance – Hardware Considerations ( 硬件考量 ) Central processing unit Single threaded Multi threaded Clock speed L2 & L3 Cache Main Store Paging Faulting Disk Available space How busy are the disk arms SSD drives

11. © 2012 IBM Corporation IBM Power Systems 11 Basics of Performance – OS and Application Considerations ( 操作系统与应用的考量 ) System values Auto Performance Adjust Max activity level Use of Memory Pools Do not mix different types of jobs and priorities in the same pool Remove batch jobs from *BASE by creating another batch pool One batch job to a pool is ideal Route batch jobs to *SHRPOOL1 On a shared production/development partition Create a second interactive pool *SHRPOOL2 for programmers Change programmers' job description routing data and subsystem description routing entries so their jobs run in SHRPOOL2 Run interactive & Web/Java in separate Memory pools Waits - if a process is NOT running it is Waiting. Idle: waiting for a work request; ie “Enter” key to be pressed Blocked: waits that occur while performing a work request

12. © 2012 IBM Corporation IBM Power Systems 12 What is Wait Accounting? ( 什么是等待统计 ) Wait accounting is the ability to determine what a job is doing when it is not running –When a job is not running, it is waiting –Waits may be normal, but some waits are not normal –Wait accounting can be used to determine if a wait condition is a problem IBM i has instrumented most of the wait conditions –Wait information is collected by Collection Services and Job Watcher –i Exclusive!

13. © 2012 IBM Corporation IBM Power Systems 13 Basics of Waiting ( 什么是等待 ) Two basic types of waits Idle : waiting for a work request Typically not indicative of a problem Waiting for the “Enter” key to be pressed on a 5250 display session If a problem, usually external to the machine E.g., slow arrival of work requests due to communications problem (Network) Possible, but not typical in batch jobs E.g., waiting for an entry to be placed on a data queue Blocked : waits that occur while performing a work request Blocked waits are the ones we want to take a closer look at “Outside of CPU usage and CPU queuing time, blocked waits are the reason jobs/threads take as long as they do to complete their work” http://ibmsystemsmag.blogs.com/i_can/2009/11/i-can-tell-you-why-youre-waiting.html

14. © 2012 IBM Corporation IBM Power Systems 14 A baseline is the expected performance characteristics over a defined period of time –The baseline provides the data to compare with and identify changes that occur –You may need multiple baselines due to varying business periods Day-to-day operations Month-end Year-end The baseline is the reference point for –Capacity planning and trending –Identifying impacts of changes in workloads, applications, operating system, hardware Create a Baseline ( 建立性能指标的基准线 )

15. © 2012 IBM Corporation IBM Power Systems 15 Patterns in Performance Data ( 性能数据的模式 ) Performance data typically has patterns –Daily, weekly, monthly, yearly –Understand your typical patterns –Recognize change

16. © 2012 IBM Corporation IBM Power Systems 16 Tools of the Trade ( 工具 ) Workload Estimator PLAN, PLAN, PLAN Understand your workloads Batch? Interactive? Java? DB? Use PDI data for more accurate estimation Plan to insure your system meets you needs today and into the future IBM Navigator for i Web based system management interface Work with active jobs Work with system memory pools Work with system status Work with disk status Real time system monitoring information from the Web Proper Prior Planning Prevents Poor Performance

17. © 2012 IBM Corporation IBM Power Systems 17 Tools of the trade （工具 ) Green Screen Commands WRKACTJOB WRKSYSSTS WRKSHRPOOL Real time performance monitoring WRKDSKSTS WRKSYSACT Performance Data Investigator Collection Services Job Watcher Disk Watcher Performance Explorer Basic understanding of system activity Management Central CPU utilization Disk Utilization Faulting Define Monitors and thresholds

18. © 2012 IBM Corporation IBM Power Systems 18 Tools of the Trade （工具） IBM Systems Director Manage and understand your entire enterprise Balance work between systems Manage Energy Cost Monitor performance across many nodes iDoctor for IBM i Advanced understanding for complex performance problems Fee based performance monitoring tools PEX Analyzer - CPU utilization, DASD operations, file space usage, waits, file opens Heap Analysis Tools for Java - Classes with large numbers of instances or total size, possibly leaking objects Job Watcher - Finding a non-CPU bottleneck: what are my threads waiting on (disk, journal, Java garbage collection, locks, etc)

19. © 2012 IBM Corporation IBM Power Systems 19 Analyze Performance by collecting performance data( 数据收集与分析 )  What performance tools to use? –Collection services – 5 minutes interval for the complete run duration –Job Watcher – to identify wait components –PEX Analyzer with disk read/writes start/end ops –Disk Watcher to review disk and IO related performance

20. © 2012 IBM Corporation IBM Power Systems 20 Disk Response Time may be the most important component in overall system performance in today's system Rules of thumb for categories: Good: Average response time less than 5 milliseconds Normal: Average response time between 5 and 10 milliseconds Requires analysis: anything over 10 milliseconds Establish disk response time objectives for a given application – your benchmark Dividing the total disk response time per transaction by the average number of synchronous disk I/Os per transaction Online Transaction Processing (OLTP) objectives will vary from batch processing because it may be more disk I/O intensive Waiting on Disk ( 等待磁盘 I/O) Execution speed of the processor core has a limited effect here. “A fast processor waiting fast for a DASD read is nonetheless still waiting.”

21. © 2012 IBM Corporation IBM Power Systems 21 Mixed SSD + HDD – cold and hot data (SSD+HDD 合理管理热点数据 ) Cold Hot Hot data may be only 10-20% capacity, but represent 80-90% activity  SSD offers best price performance when focused on “hot” data  HDD offers best storage cost, so focus it on “cold” data …. sort of a hierarchal approach  It is typical for data bases to have a large percentage of data which is infrequently used (“cold”) and a small percentage of data which is frequently used (“hot”) May be able to use larger HDD and/or a larger % capacity used Can run SSD closer to 100% capacity

22. © 2012 IBM Corporation IBM Power Systems 22 Network and Performance ( 网络与性能）  Network Performance is a key component to the overall application performance.  Does not matter how well tuned the system and application are, the user still experiences a slow response when running on a poor network.  External network  IBM i network configuration - –/QIBM/ProdData/OS/OSGi/templates/bin/areVerify.sh - network –Verify a variety of TCP/IP configuration settings and network characteristics – Verify TCP/IP Configuration Domain information Host table entries Interfaces – Verify DNS Lookup Performance and Correctness Retrieve IP address for local host Retrieve IP address for loopback Retrieve the host name for IP address 127.0.0.1. Execution speed of the system has a limited effect here. “A user waiting for a network response is nonetheless still waiting.”

23. © 2012 IBM Corporation IBM Power Systems 23 How to Accomplish Performance Results ( 如何实现性能调整 )  Plan  Analyze  Tools Proper Prior Planning Prevents Poor Performance

24. © 2012 IBM Corporation IBM Power Systems 24 Performance Disclaimer ( 免责声明 ) “it depends …” Performance information and recommendations in this presentation are based on measurements, analysis, and projections in a controlled environment for specific performance workloads. Your results may vary significantly and are dependent on the application and configuration. This information is provided along with general recommendations for you to better understand system performance. Information is provided *AS IS* without warranty of any kind. Like Medicine – Science is involved, but its really an Art form, ie use the performance principles, but you won’t know if its better until you try it.

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