First build-infra push to jdk8 -- try out the new build system!

[Weijun Wang]

On 04/13/2012 05:07 PM, Magnus Ihse Bursie wrote:
> On 2012-04-13 03:10, Weijun Wang wrote:
>> I'm trying it on my Linux x64 now. The first feeling is that my
>> computer is slowed down a lot more than the old build. The 4 CPUs all
>> show a near 100% usage (it's building hotspot now). The guide says I
>> can adjust it with --with-num-cores, but it's only available for
>> configure time and not make, right?
>
> Let me try to address this...
>
> First, one of the goals of the new build system is in fact to better
> utilize all available cores, to speed up build times. So when we're
> done, the dream scenario is a blazingly fast build that uses all
> available cpu power.
>
> ... however, for this first push, we have not yet parallelized the
> build, so any build time improvements are of a smaller scale and more
> the result of more efficient makefiles.
>
> ... and, we have not touched hotspot at all for this time. If you notice
> any difference at all when building hotspot, it must just be flukes.

Oh. I see all CPU 100% and then go to look at the build process, and 
it's hotspot.
>
> Also, when you say "slowed down", do you mean that the build takes
> longer, or just that the build uses more cpu time when building? The
> former is not something that would be expected, but the latter is.

Latter. It slows down the whole computer.

>
> As for the --with-num-cores, yes, it is a configure time option. The
> underlying assumption is that your hardware doesn't really change, and
> if your build system is too weak, it will be too weak at configure time
> and at all make times. With that said, it is always possible (and not
> very hard) to re-run configure if you need to tweak such a parameter.
>
>>
>> Also, the build output directory name is
>> build/linux-x64-normal-server-release/, the executables are in
>> build/linux-x64-normal-server-release/jdk/bin, and images in
>> build/linux-x64-normal-server-release/images/j2sdk-image. All my
>> existing scripts need to be modified.
>
> The output build directory is named differently, yes. If you have local
> scripts that depend on the name of output directories, you will have to
> modify those. The exact format of the automatically named output
> directories is still not cut in stone, though, so the actual names might
> change. One of the reasons for the new names is to allow multiple
> configurations in parallel, with different options such as debug level
> or target platform.

I see.

Thanks
Max

>
> /Magnus