diff --git a/documentation/ref-manual/usingpoky.xml b/documentation/ref-manual/usingpoky.xml index a7bff18b01..e2e05b2514 100644 --- a/documentation/ref-manual/usingpoky.xml +++ b/documentation/ref-manual/usingpoky.xml @@ -914,42 +914,51 @@ Build time can be an issue. - By default, the build system uses three simple controls to try and - maximize build efficiency: + By default, the build system uses simple controls to try and maximize + build efficiency. + In general, the default settings for all the following variables + result in the most efficient build times when dealing with single + socket systems (i.e. a single CPU). + If you have multiple CPUs, you might try increasing the default + values to gain more speed. + See the descriptions in the glossary for each variable for more + information: - BB_NUMBER_THREADS + BB_NUMBER_THREADS: + The maximum number of threads BitBake simultaneously executes. - BB_NUMBER_PARSE_THREADS + BB_NUMBER_PARSE_THREADS: + The number of threads BitBake uses during parsing. - PARALLEL_MAKE + PARALLEL_MAKE: + Extra options passed to the make command + during the + do_compile + task in order to specify parallel compilation on the + local build host. + + + PARALLEL_MAKEINST: + Extra options passed to the make command + during the + do_install + task in order to specify parallel installation on the + local build host. - These three variables all scale to the number of processor cores - available on the build system. - This auto-scaling ensures that the build system fundamentally takes - advantage of potential parallel operations during the build - based on the build machine's capabilities. + As mentioned, these variables all scale to the number of processor + cores available on the build system. + For single socket systems, this auto-scaling ensures that the build + system fundamentally takes advantage of potential parallel operations + during the build based on the build machine's capabilities. - If you need to achieve even faster builds than what the build system - produces by default, you can consider and implement some of the - following: + Following are additional factors that can affect build speed: - - BB_NUMBER_THREADS, - BB_NUMBER_PARSE_THREADS, and - PARALLEL_MAKE: - As previously mentioned, the build system scales the values - for these variables so you should probably not override - these to try to speed up a build. - However, for completeness regarding this list, it is worth - mentioning that you can manually override these variables - by setting them in your local.conf file. - File system type: The file system type that the build is being performed on can @@ -981,7 +990,9 @@ helps. - Using /tmp as a temporary file system: + Using tmpfs for + TMPDIR + as a temporary file system: While this can help speed up the build, the benefits are limited due to the compiler using -pipe. @@ -1013,6 +1024,11 @@ Aside from the previous list, you should keep some trade offs in mind that can help you speed up the build: + + Remove items from + DISTRO_FEATURES + that you might not need. + Exclude debug symbols and other debug information: If you do not need these symbols and other debug information,