RFR: 8273872: ZGC: Explicitly use 2M large pages [v2]

[Per Liden]

On Thu, 16 Sep 2021 08:32:04 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> Per Liden has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Review comments
>
> src/hotspot/share/gc/z/zArguments.cpp line 78:
> 
>> 76:   if (!FLAG_IS_DEFAULT(LargePageSizeInBytes) && LargePageSizeInBytes != 2 * M) {
>> 77:     vm_exit_during_initialization("Invalid -XX:LargePageSizeInBytes (only 2M large pages is supported)");
>> 78:   }
> 
> To better handle the case where the default large page size is not supported I suggest we add something like:
> 
> if (LargePageSizeInBytes != 2 * M) {
>   if (FLAG_IS_DEFAULT(LargePageSizeInBytes)) {
>     vm_exit_during_initialization("Default large page size is not supported (only 2M large pages are supported)");
>   } else {
>     vm_exit_during_initialization("Invalid -XX:LargePageSizeInBytes (only 2M large pages are supported)");
>   }
> }
> 
> Probably good to include the default size in the above print.

I talked to Stefan offline and we agreed to not do this change, since it's not quite the behavior we want.

-------------

PR: https://git.openjdk.java.net/jdk/pull/5541