[12] RFR: 8208499 NMT: Missing memory tag for Safepoint polling page

[Zhengyu Gu]

Thanks for the quick review.

On 07/30/2018 11:05 AM, Aleksey Shipilev wrote:
> On 07/30/2018 04:58 PM, Zhengyu Gu wrote:
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8208499
>> Webrev: http://cr.openjdk.java.net/~zgu/8208499/webrev.00/index.html
> 
> *) memory/allocation.hpp, is it really necessary to drop values from enum?

The values are unnecessary. Every time we add a new tag, we have to 
shift/update values, which is inconvenience and might introduce bugs.

> 
> *) services/memTracker.cpp, not sure why you need to assert this:
> 
>    54   // memory type occupies a byte
>    55   STATIC_ASSERT(mt_number_of_types <= max_jubyte);

memory type is encoded into tracking header as a byte field. The 
assertion ensures that we don't introduce more types that can overflow a 
byte.

> 
> *) runtime/NMT/SafepointPollingPages.java, excess newline:
> 
>    48
>    49

Fixed.

http://cr.openjdk.java.net/~zgu/8208499/webrev.01/

-Zhengyu

> 
> Otherwise looks good.
> 
> -Aleksey
>