Re: x86_64: Make sparsemem/vmemmap the default memory model

[JÃrn Engel]

On Mon, 12 November 2007 20:41:10 -0800, Christoph Lameter wrote:
> On Mon, 12 Nov 2007, Ray Lee wrote:
> 
> > Discontig obviously needs to die. However, FlatMem is consistently
> > faster, averaging about 2.1% better overall for your numbers above. Is
> > the page allocator not, erm, a fast path, where that matters?
> > 
> > Order	Flat	Sparse	% diff
> > 0	639	641	0.3
> 
> IMHO Order 0 currently matters most and the difference is negligible 
> there.

Is it?  I am a bit concerned about the non-monotonic distribution.
Difference starts a near-0, grows to 4.4, drops to near-0, grows to 4.9,
drops to near-0.

Order   Flat    Sparse  % diff
0       639     641     0.3
1       567     593     4.4
2       679     692     1.9
3       763     781     2.3
4       961     962     0.1
5       1356    1392    2.6
6       2224    2336    4.8
7       4869    5074    4.0
8       12500   12732   1.8
9       27926   28165   0.8
10      58578   58682   0.2

Is there an explanation for this behaviour?  More to the point, could
repeated runs also return 4% difference for order-0?

JÃrn

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