Re: [PATCH] remove zone_mem_map

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Andrew Morton wrote:
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>> This patch removes zone_mem_map from zone.
>>  By this, (generic) page_to_pfn and pfn_to_page can use the same logic.
> 
> I assume this is dependent upon unify-pfn_to_page-*.patch?
> 
yes. sorry for forgetting to write it.

>>  This modifies page_to_pfn implementation. Could anyone do performance test on NUMA ?
> 
> Do you expect there to be NUMA performance problems?  If so, how do they
> arise and what sort of tests should be run?
> 
I don't expect it. But when I posted this before (as RFC), some persons
(Martin J. Bligh and Dave Hansen) had concerns about it.

I think the heaviest users of page_to_pfn() are the page allocator and
mk_pte(page_to_pfn(page), hogehoge).

So, tests like  "mmap -> touch all -> unmap" will be good test.

powerpc and ia64 is not a good test environment, because they don't use
page_to_pfn() of generic DISCONTIG definitions.

other NUMAs (i386, x86_64 etc..) will be good.

Thanks,
-- Kame