RFR: 8155824: JDK build should tune down small apps more aggressively

[Erik Joelsson]

Looks good to me.

On my machine, the numbers are:

Before:
real 3m55.455s
user 48m19.736s
sys 7m12.815s

With suggested patch:
real 3m36.529s
user 41m12.488s
sys 6m17.110s

/Erik

On 2016-05-02 15:41, Claes Redestad wrote:
> Hi build-dev!
>
> I recently discovered that running with -XX:TieredStopAtLevel=1 can 
> speed up jmod execution a bit:
>
> http://mail.openjdk.java.net/pipermail/jigsaw-dev/2016-May/007593.html
>
> Applying this to the runner itself might be a mouthful, but it seems 
> profitable to apply this to JDK
> build itself. The question was raised if we would get benefits 
> elsewhere if we apply it to all "small"
> java targets...
>
> Some experimental results on my machine:
>
> time make images
>
> real    2m39.281s
> user    42m15.164s
> sys    3m56.388s
>
> -XX:TieredStopAtLevel=1 for jmod target only:
>
> real    2m34.913s
> user    38m18.112s
> sys    3m44.528s
>
> -XX:TieredStopAtLevel=1 for all small java targets in makefiles:
>
> real    2m29.490s
> user    35m45.944s
> sys    3m33.428s
>
> Reports indicate the real time improvement is even better on smaller 
> machines.
>
> I thus propose this patch:
> http://cr.openjdk.java.net/~redestad/8155824/webrev.01/
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8155824
>
> Thanks!
>
> /Claes