[U-Boot] [PATCH] MAKEALL: Automatically use parallel builds

[Mike Frysinger]

On Monday 08 December 2008 18:41:25 Wolfgang Denk wrote:
> Add logic to the MAKEALL script to determine the number of CPU cores
> on the system, and run a parallel build if there is more than one.
> Usually this significantrly accelerates builds.
>
> Allow to manually adjust the number of parallel make jobs by using
> the "BUILD_NCPUS" environment variable.
>
> Signed-off-by: Wolfgang Denk <wd at denx.de>
> ---
>  MAKEALL |   11 ++++++++++-
>  1 files changed, 10 insertions(+), 1 deletions(-)
>
> diff --git a/MAKEALL b/MAKEALL
> index dbed268..a16549c 100755
> --- a/MAKEALL
> +++ b/MAKEALL
> @@ -1,6 +1,15 @@
>  #!/bin/sh
>
> -: ${JOBS:=}
> +# Determine number of CPU cores if no default was set
> +: ${BUILD_NCPUS:="`getconf _NPROCESSORS_ONLN`"}
> +
> +if [ "$BUILD_NCPUS" -gt 1 ]

no point in quoting here ... if it isnt numeric, then -gt will fail, and all 
numeric values lack whitespace ...

> +then
> +	JOBS=-j`expr "$BUILD_NCPUS" + 1`
> +else
> +	JOBS=""
> +fi

i generally see the heuristic (cpus * 2) rather than (cpus + 1) ... benchmarks 
tend to favor that as well ...

but this is certainly better than previous behavior: always use -j1 ...
-mike
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