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author | Scott Rifenbark <scott.m.rifenbark@intel.com> | 2011-11-16 09:42:53 -0800 |
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committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2011-11-25 15:24:19 +0000 |
commit | affc8b985a6b059424ae67e230cdc1f1215c9977 (patch) | |
tree | b1166d0bc8f7f4416783251c9a55976af530e7f1 /documentation | |
parent | 4cb3862f6a1190ab3bf94bc827231e8ddabb8c62 (diff) | |
download | ast2050-yocto-poky-affc8b985a6b059424ae67e230cdc1f1215c9977.zip ast2050-yocto-poky-affc8b985a6b059424ae67e230cdc1f1215c9977.tar.gz |
documentation: BB_NUMBER_THREADS and PARALLEL_MAKE suggestions
Text that suggests setting the BB_NUMBER_THREADS and
PARALLEL_MAKE variables to speed build time has been updated to
suggest a setting of twice the number of host cores supported.
The 2x number came to light through a discussion on the project
mailing list initiated by Robert P. J. Day.
Reported-by: Robert P. J. Day
(From yocto-docs rev: 1846b41a595b7bd905ca828eaa04112d1533d7a1)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'documentation')
4 files changed, 11 insertions, 14 deletions
diff --git a/documentation/dev-manual/dev-manual-bsp-appendix.xml b/documentation/dev-manual/dev-manual-bsp-appendix.xml index 7b8dc6e..aecb24f 100644 --- a/documentation/dev-manual/dev-manual-bsp-appendix.xml +++ b/documentation/dev-manual/dev-manual-bsp-appendix.xml @@ -562,9 +562,10 @@ You should also be sure any other variables in which you are interested are set. Some variables to consider are <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>, both of which can greatly reduce your build time - if you are using a multi-threaded development system (e.g. values of - <filename>8</filename> and <filename>j 6</filename>, respectively are optimal - for a development machine that has four available cores).</para></listitem> + if your development system supports multiple cores. + For development systems that support multiple cores, a good rule of thumb is to set + both the <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename> + variables to twice the number of cores your system supports.</para></listitem> <listitem><para>Update the <filename>bblayers.conf</filename> file so that it includes the path to your new BSP layer. In this example you need to include the pathname to <filename>meta-mymachine</filename>. diff --git a/documentation/dev-manual/dev-manual-kernel-appendix.xml b/documentation/dev-manual/dev-manual-kernel-appendix.xml index 7ac349b..0f13344 100644 --- a/documentation/dev-manual/dev-manual-kernel-appendix.xml +++ b/documentation/dev-manual/dev-manual-kernel-appendix.xml @@ -221,9 +221,9 @@ If your host development system supports multi-core and multi-thread capabilities, you can uncomment these statements and set the variables to significantly shorten the full build time. - As a guideline, set <filename>BB_NUMBER_THREADS</filename> to twice the number - of cores your machine supports and set <filename>PARALLEL_MAKE</filename> to one and - a half times the number of cores your machine supports. + As a guideline, set both <filename>BB_NUMBER_THREADS</filename> and + <filename>PARALLEL_MAKE</filename> to twice the number + of cores your machine supports. </note> </para> <para> @@ -390,9 +390,8 @@ build time if your host supports multi-core and multi-thread capabilities: <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>. If the host system has multiple cores then you can optimize build time - by setting <filename>BB_NUMBER_THREADS</filename> to twice the number of - cores and setting <filename>PARALLEL_MAKE</filename> to one and a half times the - number of cores.</para></listitem> + by setting both these variables to twice the number of + cores.</para></listitem> <listitem><para><emphasis>Identify Your <filename>meta-kernel-dev</filename> Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the <filename>bblayers.conf</filename> file found in the diff --git a/documentation/poky-ref-manual/ref-variables.xml b/documentation/poky-ref-manual/ref-variables.xml index 6843094..fc4fb9c 100644 --- a/documentation/poky-ref-manual/ref-variables.xml +++ b/documentation/poky-ref-manual/ref-variables.xml @@ -927,7 +927,7 @@ This variable is usually in the form <filename>-j 4</filename>, where the number represents the maximum number of parallel threads make can run. If you development host supports multiple cores a good rule of thumb is to set - this variable to one and a half times the number of cores on the host.</para> + this variable to twice the number of cores on the host.</para> </glossdef> </glossentry> diff --git a/documentation/yocto-project-qs/yocto-project-qs.xml b/documentation/yocto-project-qs/yocto-project-qs.xml index fcbf3a1..23e097b 100644 --- a/documentation/yocto-project-qs/yocto-project-qs.xml +++ b/documentation/yocto-project-qs/yocto-project-qs.xml @@ -410,11 +410,8 @@ <ulink url='http://www.yoctoproject.org/docs/latest/poky-ref-manual/poky-ref-manual.html#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink> variables. By default, these variables are commented out. However, if you have a multi-core CPU you might want to uncomment - the lines and set the variable - <filename>BB_NUMBER_THREADS</filename> equal to twice the number of your + the lines and set both variables equal to twice the number of your host's processor cores. - Also, you could set the variable <filename>PARALLEL_MAKE</filename> equal to - 1.5 times the number of processor cores. Setting these variables can significantly shorten your build time. </para> |