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href="dbg.html#stop_clear-0">stop_clear/0</a></li> </ul> </li> <li id="loadscrollpos" title="erts_alloc_config " expanded="true">erts_alloc_config<ul> <li><a href="erts_alloc_config.html"> Top of manual page </a></li> <li title="save_scenario-0"><a href="erts_alloc_config.html#save_scenario-0">save_scenario/0</a></li> <li title="make_config-0"><a href="erts_alloc_config.html#make_config-0">make_config/0</a></li> <li title="make_config-1"><a href="erts_alloc_config.html#make_config-1">make_config/1</a></li> <li title="stop-0"><a href="erts_alloc_config.html#stop-0">stop/0</a></li> </ul> </li> </ul> </div></div> <div id="content"> <div class="innertube"> <!-- refpage --><center><h1>erts_alloc_config</h1></center> <h3>MODULE</h3> <div class="REFBODY">erts_alloc_config</div> <h3>MODULE SUMMARY</h3> <div class="REFBODY">Configuration tool for erts_alloc</div> <h3>DESCRIPTION</h3> <div class="REFBODY"><p> <div class="note"> <div class="label">Note</div> <div class="content"><p> <p><span class="code">erts_alloc_config</span> is currently an experimental tool and might be subject to backward incompatible changes.</p> </p></div> </div> <p><span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erts_alloc.html');">erts_alloc(3)</a></span> is an Erlang Run-Time System internal memory allocator library. <span class="code">erts_alloc_config</span> is intended to be used to aid creation of an <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erts_alloc.html');">erts_alloc(3)</a></span> configuration that is suitable for a limited number of runtime scenarios. The configuration that <span class="code">erts_alloc_config</span> produce is intended as a suggestion, and may need to be adjusted manually.</p> <p>The configuration is created based on information about a number of runtime scenarios. It is obviously impossible to foresee every runtime scenario that can occur. The important scenarios are those that cause maximum or minimum load on specific memory allocators. Load in this context is total size of memory blocks allocated.</p> <p>The current implementation of <span class="code">erts_alloc_config</span> concentrate on configuration of multi-block carriers. Information gathered when a runtime scenario is saved is mainly current and maximum use of multi-block carriers. If a parameter that change the use of multi-block carriers is changed, a previously generated configuration is invalid and <span class="code">erts_alloc_config</span> needs to be run again. It is mainly the single block carrier threshold that effects the use of multi-block carriers, but other single-block carrier parameters might as well. If another value of a single block carrier parameter than the default is desired, use the desired value when running <span class="code">erts_alloc_config</span>.</p> <p>A configuration is created in the following way:</p> <ul> <li> <p>Pass the <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erts_alloc.html#Mea');">+Mea config</a></span> command-line flag to the Erlang runtime system you are going to use for creation of the allocator configuration. It will disable features that prevent <span class="code">erts_alloc_config</span> from doing its job. Note, you should <strong>not</strong> use this flag when using the created configuration. Also note that it is important that you use the same <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html#+S');">amount of schedulers</a></span> when creating the configuration as you are going the use on the system using the configuration.</p> </li> <li> <p>Run your applications with different scenarios (the more the better) and save information about each scenario by calling <span class="bold_code"><a href="#save_scenario-0">save_scenario/0</a></span>. It may be hard to know when the applications are at an (for <span class="code">erts_alloc_config</span>) important runtime scenario. A good approach may therefore be to call <span class="bold_code"><a href="#save_scenario-0">save_scenario/0</a></span> repeatedly, e.g. once every tenth second. Note that it is important that your applications reach the runtime scenarios that are important for <span class="code">erts_alloc_config</span> when you are saving scenarios; otherwise, the configuration may perform bad.</p> </li> <li> <p>When you have covered all scenarios, call <span class="bold_code"><a href="#make_config-1">make_config/1</a></span> in order to create a configuration. The configuration is written to a file that you have chosen. This configuration file can later be read by an Erlang runtime-system at startup. Pass the command line argument <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html#args_file');">-args_file FileName</a></span> to the <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html');">erl(1)</a></span> command.</p> </li> <li> <p>The configuration produced by <span class="code">erts_alloc_config</span> may need to be manually adjusted as already stated. Do not modify the file produced by <span class="code">erts_alloc_config</span>; instead, put your modifications in another file and load this file after the file produced by <span class="code">erts_alloc_config</span>. That is, put the <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html#args_file');">-args_file FileName</a></span> argument that reads your modification file later on the command-line than the <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html#args_file');">-args_file FileName</a></span> argument that reads the configuration file produced by <span class="code">erts_alloc_config</span>. If a memory allocation parameter appear multiple times, the last version of will be used, i.e., you can override parameters in the configuration file produced by <span class="code">erts_alloc_config</span>. Doing it this way simplifies things when you want to rerun <span class="code">erts_alloc_config</span>.</p> </li> </ul> <div class="note"> <div class="label">Note</div> <div class="content"><p> <p>The configuration created by <span class="code">erts_alloc_config</span> may perform bad, ever horrible, for runtime scenarios that are very different from the ones saved when creating the configuration. You are, therefore, advised to rerun <span class="code">erts_alloc_config</span> if the applications run when the configuration was made are changed, or if the load on the applications have changed since the configuration was made. You are also advised to rerun <span class="code">erts_alloc_config</span> if the Erlang runtime system used is changed.</p> </p></div> </div> <p><span class="code">erts_alloc_config</span> saves information about runtime scenarios and performs computations in a server that is automatically started. The server register itself under the name <span class="code">'__erts_alloc_config__'</span>.</p> </p></div> <h3>EXPORTS</h3> <p><a name="save_scenario-0"><span class="bold_code">save_scenario() -> ok | {error, Error}</span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Error = term()</span><br> </div> </div> <div class="REFBODY"><p> <p><span class="code">save_scenario/0</span> saves information about the current runtime scenario. This information will later be used when <span class="bold_code"><a href="#make_config-0">make_config/0</a></span>, or <span class="bold_code"><a href="#make_config-1">make_config/1</a></span> is called.</p> <p>The first time <span class="code">save_scenario/0</span> is called a server will be started. This server will save runtime scenarios. All saved scenarios can be removed by calling <span class="bold_code"><a href="#make_config-0">stop/0</a></span>.</p> </p></div> <p><a name="make_config-0"><span class="bold_code">make_config() -> ok | {error, Error}</span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Error = term()</span><br> </div> </div> <div class="REFBODY"><p> <p>This is the same as calling <span class="bold_code"><a href="#make_config-1">make_config(group_leader())</a></span>.</p> </p></div> <p><a name="make_config-1"><span class="bold_code">make_config(FileNameOrIODev) -> ok | {error, Error}</span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">FileNameOrIODev = string() | io_device()</span><br> </div> <div class="REFTYPES"> <span class="bold_code">Error = term()</span><br> </div> </div> <div class="REFBODY"><p> <p><span class="code">make_config/1</span> uses the information previously saved by <span class="bold_code"><a href="#save_scenario-0">save_scenario/0</a></span> in order to produce an <span class="code">erts_alloc</span> configuration. At least one scenario have had to be saved. All scenarios previously saved will be used when creating the configuration. </p> <p>If <span class="code">FileNameOrIODev</span> is a <span class="code">string()</span>, <span class="code">make_config/1</span> will use <span class="code">FileNameOrIODev</span> as a filename. A file named <span class="code">FileNameOrIODev</span> is created and the configuration will be written to that file. If <span class="code">FileNameOrIODev</span> is an <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','io.html');">io_device()</a></span> (see the documentation of the module <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','io.html');">io</a></span>), the configuration will be written to the io device.</p> </p></div> <p><a name="stop-0"><span class="bold_code">stop() -> ok | {error, Error}</span></a><br></p> <div class="REFBODY"> <p>Types:</p> <div class="REFTYPES"> <span class="bold_code">Error = term()</span><br> </div> </div> <div class="REFBODY"><p> <p>Stops the server that saves runtime scenarios.</p> </p></div> <h3><a name="id346540">See Also</a></h3> <div class="REFBODY"> <p><span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erts_alloc.html');">erts_alloc(3)</a></span>, <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','erts','erl.html');">erl(1)</a></span>, <span class="bold_code"><a href="javascript:erlhref('../../../../doc/../','stdlib','io.html');">io(3)</a></span></p> </div> </div> <div class="footer"> <hr> <p>Copyright © 1999-2011 Ericsson AB. 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