Re: Nick's core remove PageReserved broke vmware...

[Gleb Natapov]

On Thu, Nov 03, 2005 at 02:59:44PM +0000, Hugh Dickins wrote:
> > By the way, as a separate issue, we still have a problem with DMA to pages
> > which are *needed* by the child process. What do you think about VM_COPY
> > (to do the old unix thing of actually copying the page instead of
> > setting the COW flag) and a matching madvise call to set/clear it?
> 
> I don't much want to add another path into copy_pte_range, actually
> copying pages.  If the process really wants DMA into such areas,
> then it should contain the code for the child to COW them itself?
> 
I think MPI is the main consumer of Infiniband currently. Unfortunately
it's only a library and can't control what users do before or after
fork in their applications. It is good to have possibility to copy partially 
registered pages, there shouldn't be many after all.

--
			Gleb.
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