Re: CPA patchset

dean gaudet
2008-01-11T17:02:56Z

On Fri, 11 Jan 2008, Ingo Molnar wrote:

> * Andi Kleen <ak@suse.de> 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