On Thu, 2004-06-24 at 20:11, Yasunori Goto wrote:

I understand this idea at last.
Section size of DLPAR of PPC is only 16MB.
But kmalloc area of virtual address have to be contigous 
even if the area is divided 16MB physically.
Dave-san's implementation (it was for IA32) was same index between 
phys_section and mem_section. So, I was confused.

quoted

pfn_to_page(unsigned long pfn)
{
       return
&mem_section[phys_section[pfn_to_section(pfn)]].mem_map[section_offset_pfn(pfn)];
}

But, I suppose this translation might be too complex.

It certainly doesn't look pretty, but I think it's manageable with a
comment, or maybe breaking the operation up into a few lines instead.

I worry that many person don't like this which is cause of
performance deterioration.

There is some precedent in the kernel for a table such as this.  Take a
look at the NUMA page_to_pfn() and page_zone() functions.  They use a
zone_table array to do that same kind of thing.

Are you worried bout the pfn_to_page() function itself, that it will
pull in 2 cachelines of data: 1 for phys_section[] and another for
mem_section[]?

Should this translation be in common code?

What do you mean by common code?  It should be shared by all
architectures.

-- Dave

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