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Re: Changing the default 32-bit x86 arch for Fedora 12



On Thu, Jun 18, 2009 at 02:13:11AM +0200, Kevin Kofler wrote:
> David Woodhouse wrote:
> > I'm after a system-wide answer, not a microbenchmark for zlib or crypto
> > code. It should take into account any overheads involved in
> > saving/restoring registers on context switch that wouldn't otherwise
> > have to be saved/restored.
> 
> Doesn't the kernel have to save/restore them anyway? Or how does it know
> that a program doesn't contain any SSE assembly?
> 

Turn off the fpu, let it trap, set a flag, restart the instruction with
the fpu enabled, if it happens often enough on the task, do it
unconditionally.

Magic.

	Kyle


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