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diff --git a/docs/minimumTAO.html b/docs/minimumTAO.html deleted file mode 100644 index db4d70fd15e..00000000000 --- a/docs/minimumTAO.html +++ /dev/null @@ -1,475 +0,0 @@ -<!-- $Id$ --> - -<html> - <head> - <title>Minimum TAO</title> - <link rev=made href="mailto:tao-users@cs.wustl.edu"> - </head> - -<body text = "#000000" - link="#000fff" - vlink="#ff0f0f" - bgcolor="#ffffff"> - -<hr> -<p> - -<strong>Minimum TAO</strong> -<p> - -In addition to our work on <A HREF="ACE-subsets.html">ACE -subsetting</A>, we have also been reducing the footprint of TAO. We -are pursuing two complementary strategies to reduce TAO's footprint: - -<OL> - -<LI> <B><EM>Implicit subsetting</EM></B>, e.g., by reducing - dependencies in the TAO library so that programs need not link - unused TAO components. <P> - -<LI> <B><EM>Explicit subsetting</EM></B>, e.g., by supporting the <a -href="http://www.omg.org/cgi-bin/doc?orbos/98-08-04.pdf"><em>minimumCORBA -</em></a> specification to <a href = -"http://www.cs.wustl.edu/~schmidt/TAO.html">TAO</a>. The <em> -minimumCORBA </em> specification removes the following features from -the <a href -="http://www.omg.org/technology/documents/formal/">CORBA</a> -specification. <P> -<ul> -<li>Dynamic Skeleton Interface<br> -<li>Dynamic Invocation Interface<br> -<li>Dynamic Any<br> -<li>Interceptors<br> -<li>Interface Repository<br> -<li>Advanced POA features<br> -<li>CORBA/COM interworking<br> -</ul> -</OL> - -The implicit subsetting of TAO requires no explicit application -programmer intervention. In contrast, to minimize the footprint of -TAO explicitly, you must -<OL> -<LI> <a -href="../ACE-INSTALL.html">Configure</a> ACE to support only those -components that are required by TAO and <P> -<LI> <a href = -"../TAO/TAO-INSTALL.html">Configure</a> TAO to only support the -components specified by the <em>minimumCORBA</em> specification. -</OL> - -The following two tables show the footprint reduction achievable via -explicit subsetting. Note that the IDL Compiler column refers to the -code required to collaborate between the IDL compiler and the ORB, and -not to the code for the IDL compiler itself. - -<p><hr width=50% align=left> <p> - -Note: All measurement are for ACE 5.0 and TAO 1.0 using egcs-2.91.60 -on SunOS5.7<P> - -The <a -href="../ACE-INSTALL.html#flags">make -flags</a> options used were: <P> - -<code> debug=0 optimize=1 static_libs_only=1 DEFFLAGS=-DACE_USE_RCSID=0 </code> <P> - -These options translate into:<P> -<UL> -<LI> No debugging -<LI> Optimization is set to -O2 -<LI> Static ACE and TAO libraries -<LI> Use of RCS Ids is turned off -</UL> -<p> - -To build a TAO static library, if shared libraries are the default, -use <code>make static_libs_only=1</code> (make sure to do this for -ACE, as well). If you're using recent versions of GNU GCC, you can -use the <A HREF="../ACE-INSTALL.html#repo">-frepo</A> option, which -typically reduces the footprint by another 25 percent. <P> - -<p><hr width=50% align=left> <p> - -<center><table cellpadding=4 border=4> - <tr> - <th>Configuration - <th>Component - <th>Total - <th>OS - <th>Utils - <th>Logging - <th>Threads - <th>Demux - <th>Connection - <th>Sockets - <th>IPC - <th>Svcconf - <th>Streams - <th>Memory - <th>Token - <th>Other - <tr> - <th rowspan=2>ACE (all components) - <th>Size, bytes - <td align=center>709.5 - <td align=center>11.9 - <td align=center>115.3 - <td align=center>13.7 - <td align=center>63.0 - <td align=center>88.0 - <td align=center>68.6 - <td align=center>16.9 - <td align=center>43.0 - <td align=center>99.8 - <td align=center>21.4 - <td align=center>29.2 - <td align=center>76.0 - <td align=center>62.9 - <tr> - <th>Percentage of<br>total size - <td align=center>100 - <td align=center>1.7 - <td align=center>16.2 - <td align=center>1.9 - <td align=center>8.9 - <td align=center>12.4 - <td align=center>9.7 - <td align=center>2.4 - <td align=center>6.0 - <td align=center>14.1 - <td align=center>3.0 - <td align=center>4.1 - <td align=center>10.7 - <td align=center>8.9 - <tr> - <th rowspan=2>ACE (TAO components) - <th>Size, bytes - <td align=center>570.7 - <td align=center>11.9 - <td align=center>115.3 - <td align=center>13.7 - <td align=center>63.0 - <td align=center>88.0 - <td align=center>68.6 - <td align=center>16.9 - <td align=center>43.0 - <td align=center>99.8 - <td align=center>21.4 - <td align=center>29.2 - <td align=center>0 - <td align=center>0 - <tr> - <th>Percentage of<br>total size - <td align=center>100 - <td align=center>2.1 - <td align=center>20.2 - <td align=center>2.4 - <td align=center>11.0 - <td align=center>15.4 - <td align=center>12.0 - <td align=center>3.0 - <td align=center>7.5 - <td align=center>17.5 - <td align=center>3.7 - <td align=center>5.1 - <td align=center>0 - <td align=center>0 - <tr> - <th>Reduction - <th>% - <td align=center>19.6 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>100 - <td align=center>100 -</table></center> - -<p><hr width=50% align=left> <p> - -<center><table cellpadding=4 border=4> - <tr> - <th>Configuration - <th>Component - <th>Total - <th>POA - <th>Pluggable Protocols - <th>Default Resources - <th>Interpretive Marshaling - <th>IDL Compiler - <th>ORB Core - <th>Dynamic Any - <tr> - <th rowspan=2>Complete TAO - <th>Size, Kbytes - <td align=center>1617.2 - <td align=center>412.5 - <td align=center>281.0 - <td align=center>32.1 - <td align=center>73.4 - <td align=center>10.7 - <td align=center>595.2 - <td align=center>212.3 - <tr> - <th>Percentage of<br>total size - <td align=center>100 - <td align=center>25.5 - <td align=center>17.4 - <td align=center>2.0 - <td align=center>4.5 - <td align=center>0.7 - <td align=center>36.8 - <td align=center>13.1 - <tr> - <th rowspan=2>Minimum TAO - <th>Size, Kbytes - <td align=center>1359.2 - <td align=center>376.2 - <td align=center>281.0 - <td align=center>32.1 - <td align=center>73.4 - <td align=center>10.7 - <td align=center>585.5 - <td align=center>0.0 - <tr> - <th>Percentage of<br>total size - <td align=center>100 - <td align=center>27.7 - <td align=center>20.7 - <td align=center>2.4 - <td align=center>5.4 - <td align=center>0.8 - <td align=center>43.1 - <td align=center>0.0 - <tr> - <th>Reduction - <th>% - <td align=center>16.0 - <td align=center>8.8 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>0 - <td align=center>1.6 - <td align=center>100 -</table></center><p> - -<HR> - -<h3><a name="Status">ACE+TAO Subsetting Work in Progress</a></h3> - -We've been tracking the footprint reduction of ACE+TAO periodically -since April, 2000. All the statistics are available <A -HREF="http://doc.ece.uci.edu/Stats/">online</A>. As the result of -this prior work, we've identified various areas for improvement that -we're now addressing. For example, the following are the remaining -areas for ACE subsetting: - - <ul> - <li><EM><B>Log_Msg decoupling</EM></B> -- We have a good start on this, but it needs work - to finish. It might be easiest to make an abstract - base class, then have ACE_Log_Msg derive from it. That way - we could remove the exposure of all the #includes in Log_Msg.cpp - to applications that don't need it. Another alternative would - be to disable compilation of Log_Msg.cpp when ACE_NLOGGING is - enabled.<p> - - <li><EM><B>Higher layer interdependencies</EM></B> -- We haven't - exhaustively tested all possible combinations of subsets. It's possible - that there are interdependencies between some layers that - we haven't yet identified and removed.<p> - - <li><EM><B>Remove reliance on multiple inheritance</EM></B> -- Multiple - inheriance is only used in a few - places in ACE. This - isn't really a subsetting problem, but is necessary to - fully take advantage of optimizations available on C++ compilers for - embedded systems.<p> - </ul> - -We anticipate that these changes should reduce the default size of ACE -by around 100-200 kbytes.<P> - -As the effort to reduce TAO's footprint continues, we are planning -several modifications for TAO that should reduce the footprint for -both the full CORBA and minimum CORBA configurations by around 300-400 -Kbytes. The list below contains an estimate of the impact of each one -of these changes, along with the estimated effort to implement them. -</P> - -<P> - <TABLE CELLPADDING=4 BORDER=4> - <TR> - <TD>Component</TD><TD>Impact</TD><TD>Effort</TD> - <TD>Description</TD> - </TR> - <TR> - <TD>TAO</TD><TD>~95 Kb</TD><TD>2 weeks</TD> - <TD> - Make RT CORBA 1.0 support optional, thereby allowing CORBA-compliant - applications to link without incurring the overhead of TAO's - RT CORBA features. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>~50 kB</TD><TD>3 weeks</TD> - <TD> - Make the CORBA Messaging components optional. - This change requires making RT-CORBA optional first. - </TD> - </TR> - <TR> - <TD>ACE</TD><TD>14 Kb</TD><TD>4 weeks</TD> - <TD> - Implement a TAO-specific Reactor. - ACE's reactor supports a number of features that TAO does not - require. Thus, a TAO-specific implementation is an important way to - reduce the footprint. - </TD> - </TR> - <TR> - <TD>ACE</TD><TD>20 Kb</TD><TD>4 weeks</TD> - <TD> - Implement a TAO-specific Service Configurator. - TAO uses the ACE Service Configurator to dynamically configure - its strategies. In many embedded applications the set of - strategies are selected at design-time, on those platforms it - would be appropriate to disable all the features to - dynamically load components into the ORB. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>10-15 Kb</TD><TD>1-2 weeks</TD> - <TD> - Eliminate duplicate code due to instantiations of string -> - pointer maps. TAO uses several such maps, they could be replaced by a - generic version, wrapped with a fully inlined (i.e. zero - footprint) adapter for type-safety. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>3-10 Kb</TD><TD>1-2 weeks</TD> - <TD> - Make message buffering strategies optional. - TAO supports policy extensions to control the outgoing oneway and AMI - request buffers. Those policies are not used by all - applications. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>10 Kb</TD><TD>2 weeks</TD> - <TD> - Make support for multiple ORBs optional. - TAO can support multiple ORBs in the same process, but most - applications only require one. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD><20 Kb</TD><TD>1 weeks</TD> - <TD> - Use lower footprint alternatives to the - <CODE>ACE_Strategy_Acceptor</CODE> and - <CODE>ACE_Strategy_Connector</CODE> classes. - TAO is using the most flexible classes in ACE to implement - acceptors and connector, but does not take advantage of this - flexibility. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>5 Kb</TD><TD>1 week</TD> - <TD> - Move the less common transport muxing and reply waiting - strategies to an optional library. - </TD> - </TR> - <TR> - <TD>ACE+TAO</TD><TD>30 Kb</TD><TD>8 weeks</TD> - <TD> - Decouple ACE (and then TAO) from the - <CODE>ACE_Thread_Manager</CODE> component. - This component is only used in the thread-per-connection - model, if we could decouple it in ACE then TAO could be - modified to only link this component when that concurrency - model is enabled. - </TD> - </TR> - <TR> - <TD>TAO</TD><TD>>50 Kb</TD><TD>6 weeks</TD> - <TD> - Move <CODE><<=</CODE> and <CODE>>>=</CODE> - operators to separate files. - Currently TAO includes nearly 500 such operators, moving them - to separate files (grouped by component?) would eliminate them - from most applications. - </TD> - </TR> - </TABLE> -</P> - -<P>In parallel with the activities described above we are pursuing -other avenues of research to find sources of rarely used or unused -code in ACE+TAO, and to modify the software to eliminate such code. -These activities include the following:</P> - -<UL> - <LI><P> - Using profiling tools, such as gprof, Quantify and True Coverage - to find unreachable code, or code only reachable in certain - applications. - </P></LI> - <LI><P> - The code TAO's IDL compiler generates for <CODE>CORBA::Any</CODE> - operators is large, so we are evaluating designs that reduce the impact of the <CODE>CORBA::Any</CODE> - type support. TAO's IDL compiler already makes that support optional. - However, for applications that require <CODE>Anys</CODE> it may be useful to separate that code - in another file to reduce the size of generated stubs and skeletons, - without losing the opportunity to use more dynamic CORBA invocation - modes. - </P></LI> - <LI><P> - The Notification Service currently depends on the Trading service to - implement the Trader Constraint Language. We are planning to break that - dependency and factor the TCL parser into a smaller library shared - by both services. - </P></LI> - <LI><P> - TAO still contains features that are rarely or never used. - Examples include the interfaces to query the well-known services and - to dynamically discover the level of security support. Those - components should only be linked (dynamically) in applications that require them. - </P></LI> - <LI><P> - The support for interceptors currently generated by the IDL compiler - can be partially refactored into common ORB code. - Moreover, we evaluating a new implementation of interceptors - that can be configured dynamically, thereby eliminating the need for - compile-time configuration flags. - </P></LI> - <LI><P> - We are planning to provide compile-time flags to eliminate certain mandatory features - in CORBA that are not used in all applications, such as IOR - parsers (corbaloc, corbaname, etc.). - </P></LI> - <LI><P> - Finally, we will perfom more code inspections to determine if template code can be - refactored into base classes and thereby shared by many objects in - the ACE+TAO implementations. - </P></LI> -</UL> - -Although we do not yet have sufficient insights to know how much -footprint reduction these activities will afford, we anticipate these -enhancements could reduce the default footprint of TAO by another -100-200 Kbytes. - -</body> -</html> |