RFR: 8255254: Split os::reserve_memory and os::map_memory_to_file interfaces [v2]

[Anton Kozlov]

On Mon, 26 Oct 2020 08:18:59 GMT, Stefan Karlsson <stefank at openjdk.org> wrote:

>> Anton Kozlov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix review findings
>
> src/hotspot/os/posix/os_posix.cpp line 343:
> 
>> 341:   //   mmap but it also may System V shared memory which cannot be uncommitted as a whole, so
>> 342:   //   chopping off and unmapping excess bits back and front (see below) would not work.
>> 343:   char* extra_base = os::reserve_memory(extra_size);
> 
> It seems like this belonged to the fd != -1 clause. It previously talked about the problems of using os::reserve_memory, and then used reserve_mmapped_memory instead in the fd != -1 case. It's not obvious to me that this comment belongs here.

Makes sense, thanks. I've restored the comment in the later version

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PR: https://git.openjdk.java.net/jdk/pull/812