On Nov 3, 2011, at 11:22 AM, Simon Glass wrote:
Hi Andy,
On Thu, Nov 3, 2011 at 12:28 AM, Andy Fleming afleming@freescale.com wrote:
The MAKEALL script cleverly runs make with the appropriate options to use all of the cores on the system, but your average U-Boot build can't make much use of more than a few cores. If you happen to have a many-core server, your builds will leave most of the system idle.
In order to make full use of such a system, we need to build multiple targets in parallel, and this requires directing make output into multiple directories. We add a BUILD_NBUILDS variable, which allows users to specify how many builds to run in parallel. I've found that 16 is too many on my system (fork starts to fail). When BUILD_NBUILDS is set greater than 1, we redefine BUILD_DIR for each build to be ${BUILD_DIR}/${target}. Also, we make "./build" the default BUILD_DIR when BUILD_NBUILDS is greater than 1.
Once each build finishes, we run make clean on its directory, to reduce the footprint, and also remove all .depend files.
As a result, we are left with a build directory with all of the built targets still there for use, which means anyone who wanted to use MAKEALL as part of a test harness can now do so.
Signed-off-by: Andy Fleming afleming@freescale.com
Inspired by all the MAKEALL improvements, I decided to clean up my old one for parallel builds. I think this version addresses the concerns raised last time...
I see an issue if I have a build in working tree already. I think we might need a distclean before starting
I also it seems this does things in clumps of BUILD_NBUILDS. What I mean is, if BUILD_NBUILDS is 4, you do 4 and wait for all 4 to finish before starting the 5th job once the 1st is complete. Anything we can do about that to always try and have 4 builds going until the end?
- k