RFR: JDK-8134161 JVM is creating too many GC helper threads on T7/M7 linux/sparc platform

[Gerald Thornbrugh]

Hi  Vladimir,

Thanks!

Jerry
> Looks good.
>
> Thanks,
> Vladimir
>
> On 8/31/15 12:27 PM, Gerald Thornbrugh wrote:
>> Hi,
>>
>> There is a Linux/SPARC related issue in JDK8 and JDK9 where hotspot does
>> not identify a SPARC T7/M7
>> platform correctly.  Because hotspot does not identify the T7/M7
>> platform correctly it uses the default
>> number of GC helper threads which is twice the number that is should
>> use.  The fix adds code to
>> detect a M series platform from the /proc/cpuinfo file and sets the
>> correct CPU features.  Setting the
>> correct features allow the correct number of GC helper threads to be
>> allocated.
>>
>> The fix only impacts the Linux/SPARC code and does not impact any other
>> platform/OS combination.
>>
>> I have completed successful JPRT test runs for each set of changes and
>> have also verified that the change
>> addresses the issue on Linux/SPARC M series hardware.
>>
>> Here is the bug:
>>
>> https://bugs.openjdk.java.net/browse/JDK-8134161
>>
>> Here is the JDK9 webrev:
>>
>> http://cr.openjdk.java.net/~gthornbr/8134161/webrev/
>> <http://cr.openjdk.java.net/%7Egthornbr/8134161/webrev/>
>>
>> Here is the JDK8 webrev:
>>
>> http://cr.openjdk.java.net/~gthornbr/8134674/webrev/
>> <http://cr.openjdk.java.net/%7Egthornbr/8134674/webrev/>
>>
>> Please let me know if you have any questions or concerns.
>>
>> Thanks,
>>
>> Gerald Thornbrugh