build: turn on package parallel builds by default and fix descriptions.

By default, this is only used when building with make -j.

SVN-Revision: 33582

diff --git a/Config.in b/Config.in
index e5b3346fe20a90d6b3855c94dadce824a141fb53..bd4f63ea43f8647048744826a15ac7331bf479ab 100644 (file)
--- a/Config.in
+++ b/Config.in
@@ -296,23 +296,12 @@ menu "Global build settings"
        config PKG_BUILD_PARALLEL
                bool
                prompt "Compile certain packages parallelized"
-               default n
+               default y
                help
                  This adds a -jX option to certain packages that are known to
-                 behave well for parallel build.
-
-                 Note that this may overcommit CPU resources depending on the
-                 -j level of the main make process, the number of package
-                 submake jobs selected below and the number of actual CPUs present.
-                 Example: If the main make is passed a -j4 and the submake -j
-                 is also set to 4, we may end up with 16 parallel make processes
-                 in the worst case.
-
-                 You get maximum build performance, if you set the package build
-                 jobs to the number of CPUs (cores) available and also start the main
-                 make process with -jX, where X is the number of CPUs (cores).
-                 However, make sure you have enough RAM available for
-                 NR_CPUS to the power of two (NR_CPUS^2) make jobs.
+                 behave well for parallel build. By default the package make processes
+                 use the main jobserver, in which case this option only takes effect
+                 when you add -jX to the make command.
 
                  If you are unsure, select N.
 
@@ -325,6 +314,14 @@ menu "Global build settings"
                  This passes the main make process jobserver fds to package builds,
                  enabling full parallelization across different packages
 
+                 Note that disabling this may overcommit CPU resources depending on the
+                 -j level of the main make process, the number of package
+                 submake jobs selected below and the number of actual CPUs present.
+                 Example: If the main make is passed a -j4 and the submake -j
+                 is also set to 4, we may end up with 16 parallel make processes
+                 in the worst case.
+
+
        config PKG_BUILD_JOBS
                int
                prompt "Number of package submake jobs (2-512)"