Re: CPA patchset

[dean gaudet]

On Fri, 11 Jan 2008, Ingo Molnar wrote:

> * Andi Kleen <ak@xxxxxxx> wrote:
> 
> > Cached requires the cache line to be read first before you can write 
> > it.
> 
> nonsense, and you should know it. It is perfectly possible to construct 
> fully written cachelines, without reading the cacheline first. MOVDQ is 
> SSE1 so on basically in every CPU today - and it is 16 byte aligned and 
> can generate full cacheline writes, _without_ filling in the cacheline 
> first.

did you mean to write MOVNTPS above?


> Bulk ops (string ops, etc.) will do full cacheline writes too, 
> without filling in the cacheline.

on intel with fast strings enabled yes.  mind you intel gives hints in
the documentation these operations don't respect coherence... and i
asked about this when they posted their memory ordering paper but got no
response.

-dean
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