75 lines
4.8 KiB
HTML
75 lines
4.8 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE html
|
|
PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
|
<html lang="en-us" xml:lang="en-us">
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<meta name="security" content="public" />
|
|
<meta name="Robots" content="index,follow" />
|
|
<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
|
|
<meta name="DC.Type" content="concept" />
|
|
<meta name="DC.Title" content="Comparison of Just-In-Time compiler and direct processing" />
|
|
<meta name="abstract" content="If you are trying to decide whether to use the Just-In-Time compiler or direct processing mode to run your Java program, this table provides additional information to help you make the best choice for your situation." />
|
|
<meta name="description" content="If you are trying to decide whether to use the Just-In-Time compiler or direct processing mode to run your Java program, this table provides additional information to help you make the best choice for your situation." />
|
|
<meta name="DC.Relation" scheme="URI" content="jit.htm" />
|
|
<meta name="copyright" content="(C) Copyright IBM Corporation 2006" />
|
|
<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 2006" />
|
|
<meta name="DC.Format" content="XHTML" />
|
|
<meta name="DC.Identifier" content="jitde" />
|
|
<meta name="DC.Language" content="en-us" />
|
|
<!-- All rights reserved. Licensed Materials Property of IBM -->
|
|
<!-- US Government Users Restricted Rights -->
|
|
<!-- Use, duplication or disclosure restricted by -->
|
|
<!-- GSA ADP Schedule Contract with IBM Corp. -->
|
|
<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
|
|
<link rel="stylesheet" type="text/css" href="./ic.css" />
|
|
<title>Comparison of Just-In-Time compiler and direct processing</title>
|
|
</head>
|
|
<body id="jitde"><a name="jitde"><!-- --></a>
|
|
<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
|
|
<h1 class="topictitle1">Comparison of Just-In-Time compiler and direct processing</h1>
|
|
<div><p>If you are trying to decide whether to use the Just-In-Time compiler
|
|
or direct processing mode to run your Java™ program, this table provides additional
|
|
information to help you make the best choice for your situation.</p>
|
|
<p><a href="selmod.htm">Just-In-Time compiler or direct processing mode</a></p>
|
|
|
|
<div class="tablenoborder"><table cellpadding="4" cellspacing="0" summary="" width="100%" frame="border" border="1" rules="all"><thead align="left"><tr><th valign="top" id="d0e24">Just-In-Time compiler</th>
|
|
<th valign="top" id="d0e26">Direct processing</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody><tr><td valign="top" headers="d0e24 ">Provides an automatic compilation of any method when needed. The JIT
|
|
compiler can compile a method much faster than direct processing.</td>
|
|
<td valign="top" headers="d0e26 ">Allows you to compile an entire class or JAR file by using the Create Java Program
|
|
(CRTJVAPGM) control language (CL) command. If you do not compile the files,
|
|
direct processing compiles the files automatically at run time.</td>
|
|
</tr>
|
|
<tr><td valign="top" headers="d0e24 ">Enables you to avoid using the CRTJVAPGM CL command during program
|
|
development. You can also use the JIT compiler with highly dynamic
|
|
applications that generate or discover code at run time.</td>
|
|
<td valign="top" headers="d0e26 ">Most ready-to-deploy server applications use direct processing at optimization
|
|
level 40 because they are likely to be in use by multiple users at any given
|
|
time. Multiple user jobs share the same code space in memory, which reduces
|
|
the memory footprint.</td>
|
|
</tr>
|
|
<tr><td valign="top" headers="d0e24 ">Rapidly performs complex optimizations and Java specific optimizations at run time.</td>
|
|
<td valign="top" headers="d0e26 ">Enables complex optimizations, because direct processing does not perform
|
|
optimization at run time. However, direct processing cannot always perform
|
|
Java-specific optimizations (like inlining methods) because Java program
|
|
objects must be independent.</td>
|
|
</tr>
|
|
<tr><td valign="top" headers="d0e24 ">Offers better code performance when compared to direct processing.
|
|
In most cases, the performance of JIT-generated code is better than direct
|
|
processing optimization level 40.</td>
|
|
<td valign="top" headers="d0e26 ">Offers the only way your Java program can adopt owner authority.</td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
<div>
|
|
<div class="familylinks">
|
|
<div class="parentlink"><strong>Parent topic:</strong> <a href="jit.htm" title="A Just-In-Time (JIT) compiler is a platform-specific compiler that generates machine instructions for each method as needed.">Just-In-Time compiler</a></div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html> |