AS400性能调整..doc

AS400 Performance Turning 一、Concept Response Time 1、Duration from press of button to the release of another input Job States 1、Active exists in main storage and processes work requested by the application 2、Wait needs a resource that is not available 3、Ineligible the system is unable to accept more work at that time. Wait States 1、Short Wait holds an available activity level while waiting for an activity to occur. (ex. Sndbrkmsg, write) A job can remain in short wait for a maximum of 2 seconds. Long Wait job leaves activity level. (ex. Key/think, record lock) 3、Short Wait Extended short wait to long way transition Activity Level 1、Restricts the number of jobs in main storage at one time 2、Assures the job system resource Ineligible Queue 1、Not enough resources are available, jobs become ineligible 2、It is placed in the ineligible queue until an activity level is available. 3、Long wait state job normally FIFO 4、Short wait extended or long wait caused by lock conflict it places in front of the queue. Process Access Group the variables and data in the application do not have the same values for all jobs using the application. These portions of the application and other unique objects are packaged as an object called a process access group and can be paged in or out in one operations. Time Slice 1、Amount of processing unit time allowed for each transaction. 2、If no jobs of equal or higher priority are on the ineligible queue, the job is given another time slice, remains in main storage, and continues the transaction. Else, job move to ineligible queue or time slice end pool (*BASE) Purge (*Yes) / (*No) —清除 “性能工具”的一个作业属性，指定当作业进入一个漫长等待或者离开活动层时，是否将一作业标志为可选来从主存储器移出至辅助存储器。 1、Specify purge (*yes) in job class for most of the environment and system determine the efficiency of writing of PAG 2、Purge (*no) may cause fewer writes reduce disk use less processing unit time more main storage Expert Cache (专家高速缓存) OS/400 操作系统的存储管理功能的扩充，它允许单级存储体系结构充分利用主存储器（高速缓存）的容量。