RFR: 8253332: ZGC: Make heap views reservation platform independent [v2]

[Aleksey Shipilev]

On Fri, 18 Sep 2020 08:44:11 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> ZVirtualMemoryManager::reserve_contiguous_platform tries to reserve three views of a given address range. The posix and
>> windows versions are more or less duplicates, with calls to platform dependent versions of reserve/unreserve functions.
>> I'd like to clean this up in preparation of an alternative implementation for heap memory allocation on Windows.
>> 
>> I choose to prefix the OS dependent functions with os_. For consistency, initialize_os should have been renamed as
>> well, but the plan is to change that in a separate patch that splits that function into two, so I skipped it for now.
>
> Stefan Karlsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review 1

Looks fine to me.

src/hotspot/os/posix/gc/z/zVirtualMemory_posix.cpp line 45:

> 43:   if (res != addr) {
> 44:     // Failed to reserve memory at the requested address
> 45:     munmap((void*)res, size);

No assert for `munmap` result? I don't care either way, but it would probably be nice to capture this.

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Marked as reviewed by shade (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/236