Re: [PATCH 1/4] x86_64: Switch to SPARSE_VIRTUAL

[Andy Whitcroft <apw@shadowen.org>]

Andi Kleen wrote:
> On Monday 02 April 2007 23:56:08 Dave Hansen wrote:
>> On Mon, 2007-04-02 at 14:28 -0700, Christoph Lameter wrote:
>>> I do not care what its called as long as it 
>>> covers all the bases and is not a glaring performance regresssion (like 
>>> SPARSEMEM so far). 
>> I honestly don't doubt that there are regressions, somewhere.  Could you
>> elaborate, and perhaps actually show us some numbers on this?  Perhaps
>> instead of adding a completely new model, we can adapt the existing ones
>> somehow.
> 
> If it works I would be inclined to replaced old sparsemem with Christoph's
> new one on x86-64. Perhaps that could cut down the bewildering sparsemem
> ifdef jungle that is there currently.
> 
> But I presume it won't work on 32bit because of the limited address space?

Right.  But we might be able to do switch SPARSEMEM_EXTREME users here
if performance is better and no other regressions are detected.

There seems to be a theme, we need to get some numbers.  I will try and
get what I can with the hardware I have and see whats missing.

> 
>> But, without some cold, hard, data, we mere mortals without the 1024-way
>> machines can only guess. ;)


-apw