From 1c0488792d245101ceb4efca2223574c44fd0e67 Mon Sep 17 00:00:00 2001
From: Michael Hope <michael.hope@linaro.org>
Date: Thu, 29 Sep 2011 12:40:42 +1300
Subject: config: add a 'auto' value for the number of parallel jobs

When CT_PARALLEL_JOBS is -1, set the number of parallel jobs to the
number of online CPUs + 1.  Update documentation to match.

I find this useful when building in the cloud.  You can use the same
.config file and have the build adapt to the number of processors
available.  Limited testing shows that NCPUS+1 is faster than NCPUS+0
or NCPUS+2.

Signed-off-by: Michael Hope <michael.hope@linaro.org>

diff --git a/config/global/build-behave.in b/config/global/build-behave.in
index ebf08b2..7092a7f 100644
--- a/config/global/build-behave.in
+++ b/config/global/build-behave.in
@@ -16,6 +16,8 @@ config PARALLEL_JOBS
       
       Enter 1 (or 0) to have only one job at a time.
 
+      Enter -1 to set automatically based on how many processors the host has.
+
 config LOAD
     int
     prompt "Maximum allowed load" if ! BACKEND
diff --git a/scripts/crosstool-NG.sh.in b/scripts/crosstool-NG.sh.in
index c2f35f6..6b6aa0e 100644
--- a/scripts/crosstool-NG.sh.in
+++ b/scripts/crosstool-NG.sh.in
@@ -488,7 +488,11 @@ if [ -z "${CT_RESTART}" ]; then
 
     # And help make go faster
     JOBSFLAGS=
-    [ ${CT_PARALLEL_JOBS} -ne 0 ] && JOBSFLAGS="${JOBSFLAGS} -j${CT_PARALLEL_JOBS}"
+    # Use the number of processors+1 when automatically setting the number of
+    # parallel jobs.  Fall back to 1 if the host doesn't use GLIBC.
+    AUTO_JOBS=$((`getconf _NPROCESSORS_ONLN 2> /dev/null || echo 0` + 1))
+    [ ${CT_PARALLEL_JOBS} -eq -1 ] && JOBSFLAGS="${JOBSFLAGS} -j${AUTO_JOBS}"
+    [ ${CT_PARALLEL_JOBS} -gt 0 ] && JOBSFLAGS="${JOBSFLAGS} -j${CT_PARALLEL_JOBS}"
     [ ${CT_LOAD} -ne 0 ] && JOBSFLAGS="${JOBSFLAGS} -l${CT_LOAD}"
 
     # We need to save the real .config with kconfig's value,
-- 
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