(XS) RFR: 8148766: Test AvailableProcessors.java got wrong number of processors

[Dmitry Samersoff]

David,

Should we check that available > 0 ?

Looks good for me.

-Dmitry

On 2016-02-02 05:15, David Holmes wrote:
> Bug: https://bugs.openjdk.java.net/browse/JDK-8148766
> 
> webrev: http://cr.openjdk.java.net/~dholmes/8148766/webrev/
> 
> It seems some (arguably ill-behaved) systems can use aggressive power
> management to disable cores on the fly and at high frequency. As a
> result even using taskset the number of processors reported as available
> to the JVM can be less than what we asked for. This small tweak to the
> test simply changes the success criteria to only see more than the
> expected number of processors as an error.
> 
> Thanks,
> David
> 
> --- old/test/runtime/os/AvailableProcessors.java    2016-02-01
> 21:14:07.721558368 -0500
> +++ new/test/runtime/os/AvailableProcessors.java    2016-02-01
> 21:14:05.681443769 -0500
> @@ -27,7 +27,7 @@
> 
>  /*
>   * @test
> - * @bug 6515172
> + * @bug 6515172 8148766
>   * @summary Check that availableProcessors reports the correct value
> when running in a cpuset on linux
>   * @requires os.family == "linux"
>   * @library /testlibrary
> @@ -93,7 +93,9 @@
> 
>      static void checkProcessors(int expected) {
>          int available = Runtime.getRuntime().availableProcessors();
> -        if (available != expected)
> +        // available can dynamically drop below expected due to
> aggressive power management
> +        // but we should never have more than expected, else taskset is
> broken
> +        if (available > expected)
>              throw new Error("Expected " + expected + " processors, but
> found "
>                              + available);
>          else


-- 
Dmitry Samersoff
Oracle Java development team, Saint Petersburg, Russia
* I would love to change the world, but they won't give me the sources.