Re: [Lse-tech] Re: 10.31 second kernel compile

Davide Libenzi
2002-03-17T22:57:31Z

On Sun, 17 Mar 2002, Linus Torvalds wrote:

> In article <Pine.LNX.4.44L.0203171021090.2181-100000@imladris.surriel.com>,
> Rik van Riel <riel@conectiva.com.br> wrote:
> >
> >In other words, large pages should be a "special hack" for
> >special applications, like Oracle and maybe some scientific
> >calculations ?
>
> Yes, I think so.
>
> That said, a 64kB page would be useful for generic use.
>
> >Grabbing some bitflags in generic datastructures shouldn't
> >be an issue since free bits are available.
>
> I had large-page-support working in the VM a long time ago, back when I
> did the original VM portability rewrite. I actually exposed the kernel
> large pages to the VM, and it worked fine - I didn't even need a new
> bit, since the code just used the "large page" bit in the page table
> directly.
>
> But it wasn't ever exposed to user space, and in the end I just made the
> kenel mapping just not visible to the VM and simplified the x86
> pmd_xxx() macros. The approach definitely worked, though.

Couldn't we choose the page size depending on the map size ?
If we start mixing page sizes, what about kernel code that assumes PAGE_SIZE ?

- Davide