Re: hugepage patches

[ebiederm@xmission.com (Eric W. Biederman)]

William Lee Irwin III <wli@holomorphy.com> writes:

> On Mon, Feb 03, 2003 at 10:37:51PM -0700, Eric W. Biederman wrote:
> > current->mm->mmap_sem really doesn't provide protection if there is
> > a shared area between mappings in two different mm's.  Not a problem
> > if the code is a private mapping but otherwise...
> > Does hugetlbfs support shared mappings?  If it is exclusively
> > for private mappings the code makes much more sense than I am
> > thinking.
> 
> It's supposedly for massively shared mappings to reduce PTE overhead.

O.k.  Then the code definitely needs to handle shared mappings..

> Well, in theory there's some kind of TLB benefit, but the only thing
> ppl really care about is x86 pagetable structure gets rid of L3 space
> entirely so you don't burn 12+GB of L3 pagetables for appserver loads.

I am with the group that actually cares more about the TLB benefit.
For HPC loads there is really only one application per machine.  And with
just one page table, the only real advantage is the more efficient use
of the TLB.  

Eric
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