RFR: 8234543: ZGC: Parallel pre-touch

[Per Liden]

Thanks Stefan!

/Per

On 11/28/19 2:57 PM, Stefan Karlsson wrote:
> Looks good.
> 
> StefanK
> 
> On 2019-11-21 10:32, 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