Application Environment . . in Java Writer Data Matrix 2d barcode in Java Application Environment . .

Application Environment . . using none toproduce none in web,windows application iReport Chap. 8 PROCESS PERFORMANCE A portion of t none none he response time calculation is, of course, the time that is consumed by the application process in processing a transaction. However, tbis is not usually a major factor in response time, and it is often only a negligible factor. A transaction inquiry providing a 2-second response time might only require 50 IDSeC.

of processing time, for instance. True, a good bit of the remaining time is used up in COJDDJ.UDicatiODS and data-base management; however, a good bit of time is also committed to process 1IlIIIJageD1eI1.

These are the times that we deal with here. Virtually all of the process management considerations have been touched on in previous chapters, so most of what we will discuss here will be in the aamre of a review and consolidation of this knowledge. The delay time imposed by an application process on a traDsaction is only partly due to its actual processing time.

This delay time must also include. 1. The queue d elay incun"ed by the traDsaction as it waits in line for the process. 2.

The dispatch time incuued wbile the process is waiting for the processor. 3. The processing time of the process itself.

4. The contention for the processor with application activities of higher priority. 5.

The contention for the processor with the operating system as it handles :interrupts and other system activities. 6. The messaging time required to COIDIIlUIIicate with other processes.

. Ow8wiew From a fundame ntal conceptual viewpoint, the process enviromnent as desc:ribecl above is shown in Figure 8-1. We view a process hae in the simplest of terms .to obtain an overview tying in the above concepts as a UDified whole.

A message emas the pIOceSS"s message queue and waits in tbat queue for a time tq UDtil it reaches the head of the queue. The process receives tbis message, processes it, and passes it on to another process. Figure 8-1 shows a process rmmiDg in a processor.

The pocess bas an input queue that RCeives messages at a rate ofRand pocesses them with an average service time of tp. As the process comple1es a ttaDsactioa, it passes it on to anotber process via an iDtaplocessor message JeqUiriDg a system time of Once the process has processed a ttansaction, it reliDquishes control of the p!OCeSSOf and waits for the next traDsadion. It then gets back in line with other processes at its priority and waits for 1he processor so thai it can service 1bis DeXt traDsaction.

This is shown by the"piocess being an item waiting in a greater queuo-tb.e processor queue. The amount of time tbal1he process must wait in this queue is its dispatch time, til.

Note tbat tq IepeSents the time spent by a meUllge in aprocess queue. tllrepresents the time spent by a process in the processor queue. As shown in Figure 8-1, the process, once rmmiDg, does DOtbave the processor an to ~tself.

For one tbiDg, the opetadng system c:ousumes a portion of the processor capacity. t...

,.. Chap. 8 Process Performance ." ..

_~- - - - - - - - - - t d - - - - - - - . - - - -. .------~ ESSOR PROCESSES PROCESSOR MESSAGE QUEUE PROCESSOR QUEUE as it handles none none 110, cOmmunication with other processes, timer-list management, and SO OD. The load imposed on the processor by the operating system. is 4.

Similarly, bigher priority processes may be usmping the processor while the process is trying to run (tbis is the case of preemptive schedlJling). These bigher priority processes impose a CPU load of L". The process nquiIes tp time to complete its task.

But only (1 - Lo - L,,) of the processor is available to the process, so that in a time t;, only t; (1 - Lo - L,,) time is used on behalf of the process. l"herefore, our adWIl pmcessing time, (" once the process is given the processor, is given by. 1-4-L". (8-1). A message mivi Dg at the head of the process"s message queue must wait first for a time, "td, for the process to be cliSpatcbed and then for the processing time, Thus, the service time, ts , so far as a message is c:oncemed is. (8-2). Equation 8-2 r epzesents the effective processing time, or service time, that a mes-,.
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