Request for reviews (XS): 6951686: Using large pages on Linux prevents zero based compressed oops

[Vladimir Kozlov]

Thank you, Christian

It does not work with Solaris. I tried to pass the address to shmat() instead of 0:

   retAddr = (char *) shmat(shmid, 0, SHM_SHARE_MMU | SHM_R | SHM_W);

but the method returns NULL. It seems, specifying the address interfere with flags.
So I decided to not do it. Also this path is not used by default, only when -XX:+UseISM
is specified which is not used since Solaris 9.

Thanks,
Vladimir

Christian Thalinger wrote:
> On Tue, 2010-05-11 at 17:38 -0700, Vladimir Kozlov wrote:
>> http://cr.openjdk.java.net/~kvn/6951686/webrev
>>
>> Fixed 6951686: Using large pages on Linux prevents zero based compressed oops
>>
>> The method os::reserve_memory_special() is used with -XX:+UseLargePages on Linux.
>> It uses shared memory API to reserve memory but it does not use req_addr.
>>
>> Use req_addr when attaching shared memory segment.
> 
> I looked at the changes and it seems they are good.  I guess Solaris is
> behaving completely different and that's why this is only required on
> Linux.
> 
> -- Christian
>