RE: Even faster page copy for Xen?

[Dan Magenheimer <dan.magenheimer@oracle.com>]

I wasn't sure about that... Jan's patch to speed up
copy_page (by 12%) went in before tmem was in-tree,
so I assumed otherwise.  Clearly my interest is for
tmem, especially if 2x-4x improvement is possible,
but if there really is no significant advantage for
non-tmem code, I will put it on my list... for sometime
in the next century when I am a good x86 assembly
programmer :-)

> -----Original Message-----
> From: Keir Fraser [mailto:keir.fraser@eu.citrix.com]
> Sent: Thursday, July 15, 2010 3:35 PM
> To: Dan Magenheimer; Jan Beulich
> Cc: xen-devel@lists.xensource.com
> Subject: Re: Even faster page copy for Xen?
> 
> It has to be said, possibly tmem excepted, there is very little page
> copying
> in Xen.
> 
>  -- Keir
> 
> On 15/07/2010 19:15, "Dan Magenheimer" <dan.magenheimer@oracle.com>
> wrote:
> 
> > Hi Jan, Keir --
> >
> > My x86 assembly skills are much too poor to carefully evaluate
> > and, if of value, implement this in Xen but given your previous
> > interest, such as:
> >
> > http://xenbits.xensource.com/xen-unstable.hg?rev/8de4b4e9a435
> >
> > the following might be worth looking at.
> >
> > Intel has just posted memcpy improvements for glibc for recent
> > popular Intel processor families here:
> >
> > http://article.gmane.org/gmane.comp.lib.glibc.alpha/15278
> >
> > The preface to the above patch looks very enticing...
> >
> > Semi-related, I wonder if you know, if there were a
> > "copy_page_from_other_node()" to be used if the
> > caller is fairly sure that the page is being copied
> > between nodes, could this be made significantly faster
> > than a normal copy_page()?
> >
> > Thanks,
> > Dan
> 
>