Re: [BK PATCH 2.5] Introduce 64-bit versions of PAGE_{CACHE_,}{MASK,ALIGN}

[Russell King]

On Sun, Jul 28, 2002 at 05:10:48PM -0700, Andrew Morton wrote:
> - Remove ->virtual, do page_address() via a hash.  4(ish) bytes saved.

Hmmmmmmm.  page_address() is already 5 loads (on ARM) if page->virtual
isn't used.  I'm seriously considering changing page_address() to cover
the 3 cases more efficiently:

1. non-discontiguous case (should be around 2 loads + math)
2. discontiguous case (currently 5 loads + lots of math)
3. weirder setups where loading page->virtual is faster

We currently ignore (1) completely, and just assume its the same as (2).

-- 
Russell King ([e-mail])                The developer of ARM Linux
             http://www.arm.linux.org.uk/personal/aboutme.html