RFR(XS) 8194934: NMT: Remove MemTracker::get_virtual_memory_xxx_tracker(), create Tracker in place

[coleen.phillimore at oracle.com]

Yes, this looks good, and trivial so I think we don't need another code 
review.   I will sponsor it for you.
Thanks,
Coleen


On 2/2/18 4:35 PM, Zhengyu Gu wrote:
> MemTracker is a stack object, it locks ThreadCrtical in its 
> constructor, and unlock it in destructor.
>
> Using MemTracker::get_virtual_memory_XXX_tracker() to acquire a 
> tracker, causes an additional lock/unlock of ThreadCritical.
>
> This patch creates MemTracker in place to avoid the extra lock/unlock.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8194934
> Webrev: http://cr.openjdk.java.net/~zgu/8194934/webrev.00/
>
> Test:
>
>   hotspot_tier1_runtime on Linux 64 (fastdebug and release)
>
>   Verified minimal VM build.
>
>
> Thanks,
>
> -Zhengyu