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SubjectRe: x86_64: Make sparsemem/vmemmap the default memory model
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?

Jörn

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