RFR: 8234543: ZGC: Parallel pre-touch

[erik.osterlund at oracle.com]

Hi Per,

Still good.

Thanks,
/Erik

On 11/25/19 3:10 PM, Per Liden wrote:
> I noticed that we didn't have a test for this on ZGC, so I added one:
>
> Updated webrev: http://cr.openjdk.java.net/~pliden/8234543/webrev.1
>
> /Per
>
> On 11/21/19 10:32 AM, Per Liden wrote:
>> When using -XX:+AlwaysPreTouch, ZGC is currently doing single 
>> threaded pre-touch. This patch makes this a parallel operation. This 
>> improves startup time, especially when using large heaps. For 
>> example, when using a 3TB heap (-XX:+AlwaysPreTouch -Xms3T -Xmx3T), 
>> startup time is improved by about 30x.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8234543
>> Webrev: http://cr.openjdk.java.net/~pliden/8234543/webrev.0
>>
>> /Per