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<concept id="GUID-B77702FA-7385-51A0-986F-7667669CBDB2" xml:lang="en"><title>Guide to Optimising Performance</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This document highlights areas to investigate as part of a system-wide

performance optimization process. </p>

<section id="GUID-4B3CF640-15D0-462B-8E64-C002115DDF90"><title>Introduction</title> <p>During development much attention is devoted to functionality.

It is typically only at the later stages of development that performance

(speed, RAM use, power consumption) becomes an issue. This is inevitable

for many good reasons. </p> <ul>

<li id="GUID-32A6D5A9-4A2C-5EC0-B602-98C0B14A9487"><p>Performance

cannot be easily or usefully assessed until a device or system nears

completion. </p> </li>

<li id="GUID-572885AD-64E4-5963-AA44-7883239E33AA"><p>Performance

is often affected by interactions between components. </p> </li>

<li id="GUID-BF3A5F0F-10A1-5E44-8DA0-0A1089705B85"><p>Performance

is hardware related. </p> </li>

<li id="GUID-2363FD02-FD50-5837-A719-E976925C2F29"><p>Optimizations

can result in less easily maintained code. </p> </li>

<li id="GUID-6016203A-D493-5829-8A33-BB28DD21DDC3"><p>A few worthwhile

optimizations are much more efficient than many which have little

impact. </p> </li>

</ul> <p>This does not mean that improving or optimizing performance

should only be considered as a single activity to be performed towards

the end of a development project. Good practise and forward thinking

in all aspects from the outset are the most important contributors

to producing high-performance products. </p> <p>The Symbian Developer

Library is full of advice on how to write fast and efficient code

and how to configure your software and hardware for optimized performance. </p> </section>

<section id="GUID-7AAFD9F5-6AFD-42C6-8872-F67EA380C7EB"><title>Objectives</title> <p>Performance improvement or optimization may be described as achieving

some or all of the following: </p> <ul>

<li id="GUID-62821E16-8F93-5C56-ADD7-B1D1ACA08AFB"><p>Increased execution

speed. Applications and processes perform or appear to perform tasks

in less time. </p> </li>

<li id="GUID-DEB5147F-3932-56F4-8E46-435A2A059B38"><p>Reduced start

up time. Devices are ready for use more quickly after being switched

on. </p> <p><xref href="GUID-AF30D941-BFD8-5260-9588-C5DA6983F558.dita">System Starter</xref>  </p> </li>

<li id="GUID-83720AE2-A308-59ED-8C20-FC7981486D4C"><p>Efficient ROM

and RAM use. ROM and RAM cost money. </p> <p><xref href="GUID-EFC99FD5-4EC2-5B9E-AE03-FE66D1ABF8A8.dita">Optimising Compressed

ROMs</xref>  </p> </li>

<li id="GUID-4554E6D0-76D7-589F-924A-9724074F8A0F"><p>Reduced power

consumption. </p> </li>

</ul> </section>

<section id="GUID-A332DB15-D2A3-4596-95ED-5045DE2EA378"><title>Assessment

and Measurement</title> <p>Making changes to functioning code is a

time consuming and high-risk activity. Before making any changes,

therefore, you must be confident that you are likely to have a significant

beneficial impact and that you will be able to measure and quantify

it. </p> <p>The Symbian platform includes tools and supports techniques

that enable you to analyze, monitor and measure the performance of

your system or device. </p> <p>The Symbian Platform Sampling Profiler </p> <p><xref href="GUID-BB174A7C-9B72-55C8-8C8A-F5FB14AB3607.dita">Hardware

Debugging Tools</xref>  </p> <p>General purpose logging (UTRACE)  </p> </section>

<section id="GUID-863D9195-62F8-455E-89C2-AD1D912066A4"><title>Actions

and Activities</title> <p><b>Configuration</b> </p> <p>The Symbian platform and many of its

components support various build-time configuration parameters. These

include settings in configuration and initialization files, macro

definitions and patchable constant values. </p> <p><xref href="GUID-7E401451-16EB-515B-88B2-4D0D2D6C7A57.dita">Adjustable Performance

Configuration</xref>  </p> <p><xref href="GUID-B526BA3A-14E4-53B4-9382-437475A1C8A4.dita">List of Patchable

Constants</xref>  </p> <p><b>Coding Practise</b> </p> <p>There are many aspects of coding practise

that can result in performance variations. Though such differences

might appear small, performance bottlenecks can occur where a piece

of inefficient code is executed repeatedly. By identifying where bottlenecks

exist you target specific areas of code that have a significant impact

on performance. </p> <p><xref href="GUID-49645D0A-AEA4-5D61-A6F3-633D80DCFD5B.dita">Application Performance</xref>  </p> <p><xref href="GUID-12FF05BE-F06E-58F0-909D-05CB6F7FA03E.dita">Code Efficiency</xref>  </p> </section>

<section id="GUID-F2E2E586-E2F8-4EC2-987A-F38ED2771F14"><title>Further

Reading</title> <p>The following documents, located in other sections

of the library, discuss performance and optimization issues relating

to particular components of the operating system. </p> <ul>

<li id="GUID-EF06353C-E907-507E-8468-DC373D6E89AB"><p>Calendar: <xref href="GUID-94AC5E9C-146D-5FE7-B7B6-44AA139A6012.dita">Speeding up Agenda

Application Start-up How-To Document, in the Agenda Model engineering

documents section</xref>  </p> </li>

<li id="GUID-779BAF64-10F9-549D-AAE2-B8A13B923A13"><p>Contacts: <xref href="GUID-2E1DCE15-2F35-57E4-A279-18D1A3AB4BD3.dita">Speeding up Contacts

Application Start-up How-To Document, in the Contacts Model engineering

documents section</xref>  </p> </li>

<li id="GUID-9B7C9702-5877-51B1-87D9-573F6D9A1430"><p>Plugin Framework: <xref href="GUID-85AE95DD-D8C0-5F38-9A98-2F92328162E7.dita">Using ECOM and plug-ins

in phone ROMs</xref>  </p> </li>

<li id="GUID-97F6CBB4-928F-5EE2-857B-15999502AB98"><p>Various components: <xref href="GUID-C6C77895-91E8-5BBF-8D77-0DF6F92F1223.dita">System-level engineering

documents</xref>  </p> </li>

</ul> </section>

</conbody></concept>