diff options
| -rw-r--r-- | documentation/ref-manual/ref-variables.xml | 37 |
1 files changed, 34 insertions, 3 deletions
diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml index c330fe0..ea5b9d8 100644 --- a/documentation/ref-manual/ref-variables.xml +++ b/documentation/ref-manual/ref-variables.xml @@ -872,8 +872,26 @@ 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. + For example, a system with a dual core processor that + also uses hyper-threading causes the + <filename>BB_NUMBER_THREADS<filename> variable to default + to "4". + </para> + + <para> + For single socket systems (i.e. one CPU), you should not + have to override this variable to gain optimal parallelism + during builds. + However, if you have very large systems that employ + multiple physical CPUs, you might want to make sure the + <filename>BB_NUMBER_THREADS</filename> variable is not + set higher than "20". + </para> + + <para> + For more information on speeding up builds, see the + "<link linkend='speeding-up-the-build'>Speeding Up the Build</link>" + section. </para> </glossdef> </glossentry> @@ -8499,7 +8517,7 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3" <link linkend='ref-tasks-compile'><filename>do_compile</filename></link> task in order to specify parallel compilation on the local build host. - This variable is usually in the form "-j <x>", + This variable is usually in the form "-j <replaceable>x</replaceable>", where x represents the maximum number of parallel threads <filename>make</filename> can run. </para> @@ -8513,6 +8531,19 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3" the software being built has problems running its <filename>make</filename> process in parallel. </note> + For single socket systems (i.e. one CPU), you should not + have to override this variable to gain optimal parallelism + during builds. + However, if you have very large systems that employ + multiple physical CPUs, you might want to make sure the + <filename>PARALLEL_MAKE</filename> variable is not + set higher than "20". + </para> + + <para> + For more information on speeding up builds, see the + "<link linkend='speeding-up-the-build'>Speeding Up the Build</link>" + section. </para> </glossdef> </glossentry> |
