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dev-manual, ref-manual, yocto-project-qs: Updates to parallelism variables 

The way the old manual set had worded the use of the
BB_NUMBER_THREADS, PARALLEL_MAKE, and BB_NUMBER_PARSE_THREADS
had become depricated.  It suggested a lot of user intervention
to get these variables set to have the build system utilize
optimal parallelism.  The change a while back to the build system
where the variables are set to the number of build host cores
now makes the variables automatically be set to their best
values.  I have gone through the manual set and changed wordings
appropriately to reflect this.

Reported-by: Robert P. J. Day <rpjday@crashcourse.ca>
(From yocto-docs rev: 3a27b1792c92a2f22173315e2732f672cdad2c78)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark 2015-01-19 14:14:19 -08:00 committed by Richard Purdie
parent 0a367c514b
commit 4ab132a20d
5 changed files with 33 additions and 50 deletions
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7
documentation/dev-manual/dev-manual-start.xml
View File

@ -297,10 +297,9 @@
This file defines many aspects of the build environment including
the target machine architecture through the
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'>MACHINE</ulink></filename> variable,
the development machine's processor use through the
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'>BB_NUMBER_THREADS</ulink></filename> and
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'>PARALLEL_MAKE</ulink></filename> variables, and
a centralized tarball download directory through the
the packaging format used during the build
(<ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>),
and a centralized tarball download directory through the
<filename><ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'>DL_DIR</ulink></filename> variable.</para></listitem>
<listitem><para>
Build the image using the <filename>bitbake</filename> command.

15
documentation/ref-manual/closer-look.xml
View File

@ -162,9 +162,10 @@
<itemizedlist>
<listitem><para><emphasis>Parallelism Options:</emphasis>
Controlled by the
<link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
<link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>,
<link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>,
and
<link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>
<ulink url='&YOCTO_DOCS_BB_URL;#var-BB_NUMBER_PARSE_THREADS'><filename>BB_NUMBER_PARSE_THREADS</filename></ulink>
variables.</para></listitem>
<listitem><para><emphasis>Target Machine Selection:</emphasis>
Controlled by the
@ -216,12 +217,10 @@
For example, suppose you had several build environments and
they shared some common features.
You can set these default build properties here.
A good example is perhaps the level of parallelism you want
to use through the
<link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
and
<link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>
variables.</para>
A good example is perhaps the packaging format to use
through the
<link linkend='var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></link>
variable.</para>
<para>One useful scenario for using the
<filename>conf/site.conf</filename> file is to extend your
<link linkend='var-BBPATH'><filename>BBPATH</filename></link>

8
documentation/ref-manual/ref-structure.xml
View File

@ -467,12 +467,8 @@
<filename><link linkend='var-MACHINE'>MACHINE</link></filename>
for which you want to build, which package types you wish to use
(<link linkend='var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></link>),
the location from which you want to access downloaded files
(<filename><link linkend='var-DL_DIR'>DL_DIR</link></filename>),
and how you want your host machine to use resources
(<link linkend='var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></link>
and
<link linkend='var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></link>).
and the location from which you want to access downloaded files
(<filename><link linkend='var-DL_DIR'>DL_DIR</link></filename>).
</para>
<para>

23
documentation/ref-manual/ref-variables.xml
View File

@ -729,20 +729,17 @@
<glossentry id='var-BB_NUMBER_THREADS'><glossterm><imagedata fileref="figures/define-generic.png" />BB_NUMBER_THREADS</glossterm>
<info>
BB_NUMBER_THREADS[doc] = "The maximum number of tasks BitBake should run in parallel at any one time. A good rule of thumb is for this variable to be twice the number of cores."
BB_NUMBER_THREADS[doc] = "The maximum number of tasks BitBake should run in parallel at any one time. This variable is automatically configured to be equal to the number of build system cores."
</info>
<glossdef>
<para>
The maximum number of tasks BitBake should run in parallel
at any one time.
If your host development system supports multiple cores,
a good rule of thumb is to have this variable be twice the
number of cores.
</para>
<para>
The default value for <filename>BB_NUMBER_THREADS</filename>
is equal to the number of cores your build system has.
The OpenEmbedded build system automatically configures
this variable to be equal to the number of cores on the
build system.
To gain optimal parallelism, you should not have to
override this variable.
</para>
</glossdef>
</glossentry>
@ -7380,11 +7377,9 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
</para>
<para>
If your development host supports multiple cores, a good
rule of thumb is to set this variable to twice the number
of cores on the host.
If you do not set <filename>PARALLEL_MAKE</filename>, it
defaults to the number of cores your build system has.
The OpenEmbedded build system automatically sets this
variable to be equal to the number of cores the build
system uses.
<note>
Individual recipes might clear out this variable if
the software being built has problems running its

30
documentation/yocto-project-qs/yocto-project-qs.xml
View File

@ -509,15 +509,17 @@
</para>
<para>
Another couple of variables of interest are the
<ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink> and the
<ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink> variables.
By default, these variables are set to the number of processor
cores your build host uses.
However, if your build host uses multiple processor cores,
you should increase these settings to twice the number of
cores used.
Doing so can significantly shorten your build time.
Another three variables of interest are the
<ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink>,
<ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink>,
and
<ulink url='&YOCTO_DOCS_BB_URL;#var-BB_NUMBER_PARSE_THREADS'><filename>BB_NUMBER_PARSE_THREADS</filename></ulink>
variables.
By default, these variables are optimally set based on the
number of processor cores your build host uses.
Although it is possible to override these variables, the
default values the OpenEmbedded build system derives provide you
with parallelism during the build.
</para>
<para>
@ -898,18 +900,10 @@
<filename>conf/local.conf</filename> configuration file
in the Build Directory.
You need to manually edit this file to specify the machine you
are building and to optimize your build time.
Here are the minimal changes to make:
are building:
<literallayout class='monospaced'>
BB_NUMBER_THREADS = "8"
PARALLEL_MAKE = "-j 8"
MACHINE ?= "beaglebone"
</literallayout>
Briefly, set
<ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink>
and
<ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink> to
twice your host processor's number of cores.
</para>
<para>