Messages in this thread |  | | | Date | Sun, 1 Mar 2009 03:07:08 +0100 | | From | Andi Kleen <> | | Subject | Re: [patch] x86, mm: pass in 'total' to __copy_from_user_*nocache() |
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On Sat, Feb 28, 2009 at 05:38:13PM -0800, Arjan van de Ven wrote: > On Sun, 1 Mar 2009 02:48:22 +0100 > Andi Kleen <andi@firstfloor.org> wrote: > > > > the entire point of using movntq and friends was to save half the > > > > I thought the point was to not pollute caches? At least that is > > what I remember being told when I merged the patch. > > > > the reason that movntq and co are faster is because you avoid the > write-allocate behavior of the caches....
Not faster than rep ; movs which does similar magic anyways. Of course it being magic it can vary a lot and is somewhat unpredictable.
Also in my experince movnt is not actually that much faster for small transfers (as in what the kernel mostly does)
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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