PING: Linux: Support transparent hugepages

[Igor Veresov]

Why is alignment required? Afaik it's perfectly fine to have mixed page 
sizes in a single segment. Also, if use use +UseLargePages, all the heap 
and generation sizes will be largepage-alinged anyway. Also, some things 
like the NUMA-allocator will work better is they know kind of pages the 
underlying segment has.

What I would've done is put some logic to distinguish kernels that 
support transparent large pages and instead of using all the SHM stuff 
just use a mmap + madvise(MADV_HUGEPAGE). On Solaris we do kind of the 
same thing, but there you have to do mmap + memcntl(MC_HAT_ADVISE). 
Although Solaris 10 also supports out-of-the-box large pages, so in 
theory you don't have to do anything, but I guess it's always better to 
hint the OS that you really want it.

igor

On 4/1/11 9:31 AM, Andrew Haley wrote:
> Hi all,
>
> A little while ago I posted this question about adding support for
> Linux's transparent hugepages to HotSpot.  I'd really appreciate comments.
>
> Thanks,
> Andrew.