Re: page fault scalability patch final : i386 tested, x86_64 support added

Andrew Morton
2004-08-28T00:39:12Z

"David S. Miller" <davem@davemloft.net> wrote:
>
> On Fri, 27 Aug 2004 17:19:11 -0700 (PDT)
> Christoph Lameter <clameter@sgi.com> wrote:
>
> > That is still 2^(32+12) = 2^44 = 16TB.
>
> It's actually:
>
> 2 ^ (31 + PAGE_SHIFT)
>
> '31' because atomic_t is 'signed' and PAGE_SHIFT should
> be obvious.
>
> Christoph definitely has a point, this is even more virtual space
> than most of the 64-bit platforms even support. (Sparc64 is
> 2^43 and I believe ia64 is similar)

When can we reasonably expect someone to blow this out of the water?
Within the next couple of years, I suspect?

It does look like we need a new type which is atomic64 on 64-bit and
atomic32 on 32-bit. That could be used to fix the
mmaping-the-same-page-4G-times-kills-the-kernel bug too.

> and this limit actually
> mostly comes from the 3-level page table limits.

This reminds me - where's that 4-level pagetable patch got to?