diff options
Diffstat (limited to 'chapter04')
| -rw-r--r-- | chapter04/aboutsbus.xml | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/chapter04/aboutsbus.xml b/chapter04/aboutsbus.xml index 2961b799d..c336d29dc 100644 --- a/chapter04/aboutsbus.xml +++ b/chapter04/aboutsbus.xml @@ -32,14 +32,33 @@ Fortunately, most build times are shorter than the one for Binutils.</para> <para>In general, SBUs are not entirely accurate because they depend on many - factors, including the host system's version of GCC. Note that on Symmetric - Multi-Processor (SMP)-based machines, SBUs are even less accurate. They are - provided here to give an estimate of how long it might take to install a - package, but the numbers can vary by as much as dozens of minutes in some - cases.</para> + factors, including the host system's version of GCC. They are provided here + to give an estimate of how long it might take to install a package, but the + numbers can vary by as much as dozens of minutes in some cases.</para> <para>To view actual timings for a number of specific machines, we recommend The LinuxFromScratch SBU Home Page at <ulink url="&lfs-root;~sbu/"/>.</para> + <note><para>For many modern systems with multiple processors (or cores) the + compilation time for a package can be reduced by performing a "parallel make" + by either setting an environment variable or telling the + <command>make</command> program how many processors are available. For + instance, a Core2Duo can support two simultaneous processes with:</para> + + <screen><userinput>set MAKEFLAGS='-j 2'</userinput></screen> + + <para>or just building with:</para> + + <screen><userinput>make -j2</userinput></screen> + + <para>When multiple processors are used in this way, the SBU units in the + book will vary even more than they normally would. Analyzing the output of + the build process will also be more difficult because the lines of different + processes will be interleaved. If you run into a problem with a build step, + revert back to a single processor build to properly analyze the error + messages.</para> + + </note> + </sect1> |