From 84adefa331c4159d432d22840663c38f155cd4c1 Mon Sep 17 00:00:00 2001 From: Erlang/OTP Date: Fri, 20 Nov 2009 14:54:40 +0000 Subject: The R13B03 release. --- lib/runtime_tools/doc/src/erts_alloc_config.xml | 211 ++++++++++++++++++++++++ 1 file changed, 211 insertions(+) create mode 100644 lib/runtime_tools/doc/src/erts_alloc_config.xml (limited to 'lib/runtime_tools/doc/src/erts_alloc_config.xml') diff --git a/lib/runtime_tools/doc/src/erts_alloc_config.xml b/lib/runtime_tools/doc/src/erts_alloc_config.xml new file mode 100644 index 0000000000..5e7cbe4172 --- /dev/null +++ b/lib/runtime_tools/doc/src/erts_alloc_config.xml @@ -0,0 +1,211 @@ + + + + +
+ + 20072009 + Ericsson AB. All Rights Reserved. + + + The contents of this file are subject to the Erlang Public License, + Version 1.1, (the "License"); you may not use this file except in + compliance with the License. You should have received a copy of the + Erlang Public License along with this software. If not, it can be + retrieved online at http://www.erlang.org/. + + Software distributed under the License is distributed on an "AS IS" + basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + the License for the specific language governing rights and limitations + under the License. + + + + erts_alloc_config + Rickard Green + 1 + 07-05-30 + 1 + erts_alloc_config.sgml +
+ erts_alloc_config + Configuration tool for erts_alloc + + +

erts_alloc_config is currently an experimental + tool and might be subject to backward incompatible + changes.

+ +

erts_alloc(3) is an + Erlang Run-Time System internal memory allocator library. + erts_alloc_config is intended to be used to aid creation + of an erts_alloc(3) + configuration that is suitable for a limited number of runtime + scenarios. The configuration that erts_alloc_config + produce is intended as a suggestion, and may need to be + adjusted manually.

+

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.

+

The current implementation of erts_alloc_config 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 erts_alloc_config 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 erts_alloc_config.

+

A configuration is created in the following way:

+ + +

Pass the +Mea config + 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 erts_alloc_config from + doing it's job. Note, you should not use this flag + when using the created configuration. Also note that it is + important that you use the same + amount of schedulers + when creating the configuration as you are going the use on + the system using the configuration.

+ + +

Run your applications with different scenarios (the more + the better) and save information about each scenario by calling + save_scenario/0. + It may be hard to know when the applications are at an (for + erts_alloc_config) important runtime scenario. A good + approach may therefore be to call + save_scenario/0 + repeatedly, e.g. once every tenth second. Note that it is + important that your applications reach the runtime scenarios + that are important for erts_alloc_config when you are + saving scenarios; otherwise, the configuration may perform + bad.

+ + +

When you have covered all scenarios, call + make_config/1 + 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 + -args_file FileName + to the erl(1) command.

+ + +

The configuration produced by erts_alloc_config may + need to be manually adjusted as already stated. Do not modify the + file produced by erts_alloc_config; instead, put your + modifications in another file and load this file after the + file produced by erts_alloc_config. That is, put the + -args_file FileName + argument that reads your modification file later on the + command-line than the + -args_file FileName + argument that reads the configuration file produced by + erts_alloc_config. 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 erts_alloc_config. Doing it this way simplifies + things when you want to rerun erts_alloc_config.

+ + + +

The configuration created by erts_alloc_config 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 + erts_alloc_config 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 erts_alloc_config if the Erlang + runtime system used is changed.

+ +

erts_alloc_config saves information about runtime scenarios + and performs computations in a server that is automatically + started. The server register itself under the name + '__erts_alloc_config__'.

+ + + + save_scenario() -> ok | {error, Error} + Saves information about current runtime scenario + + Error = term() + + +

save_scenario/0 saves information about the current + runtime scenario. This information will later be used when + make_config/0, + or make_config/1 + is called.

+

The first time save_scenario/0 is called a server + will be started. This server will save runtime scenarios. All + saved scenarios can be removed by calling + stop/0.

+ + + + make_config() -> ok | {error, Error} + Creates an erts_alloc configuration + + Error = term() + + +

This is the same as calling + make_config(group_leader()).

+ + + + make_config(FileNameOrIODev) -> ok | {error, Error} + Creates an erts_alloc configuration + + FileNameOrIODev = string() | io_device() + Error = term() + + +

make_config/1 uses the information previously saved by + save_scenario/0 + in order to produce an erts_alloc configuration. At + least one scenario have had to be saved. All scenarios + previously saved will be used when creating the + configuration.

+

If FileNameOrIODev is a string(), + make_config/1 will use FileNameOrIODev as a + filename. A file named FileNameOrIODev is created and + the configuration will be written to that file. If + FileNameOrIODev is an + io_device() (see the + documentation of the module + io), the configuration + will be written to the io device.

+ + + + stop() -> ok | {error, Error} + + + Error = term() + + +

Stops the server that saves runtime scenarios.

+ + + + +
+ See Also +

erts_alloc(3), + erl(1), + io(3)

+
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