Re: [Xen-devel] [PATCH] x86: add SSE-based copy_page()

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 19/11/08 20:24, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

> I haven't had a chance to test this further yet,
> but I see the patch was already taken (c/s 18772).
> 
> Why, given that performance gets worse under some
> circumstances?  At least maybe there should be two
> interfaces: copy_page_cold_cache() and
> copy_page_warm_cache() rather than just assume?
> 
> I'll post measurements when I get a chance to test,
> but bring this up as a placeholder for now.

If more extensive testing shows it not to be a win in general then we can
revert the patch.

Looking at c/s 18724 again also I wonder what fixmap_domain_page() was
introduced for, rather than just using map_domain_page(). Is it an attempt
to reduce global TLB shootdowns? It's not very clear nor very pretty and I'd
rather just kill it and use map_domain_page().

 -- Keir



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