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From: Arnd Bergmann <arnd@arndb.de>
To: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] add Kconfig option for optimizing for cell
Date: Sat, 15 Sep 2007 03:02:52 +0200
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On Saturday 15 September 2007, Segher Boessenkool wrote:
>=20
> > +config TUNE_CELL
> > +=A0=A0=A0=A0=A0bool "Optimize for Cell Broadband Engine"
> > +=A0=A0=A0=A0=A0depends on PPC64
> > +=A0=A0=A0=A0=A0help
> > +=A0=A0=A0=A0=A0 =A0Cause the compiler to optimize for the PPE of the C=
ell Broadband
> > +=A0=A0=A0=A0=A0 =A0Engine. This will make the code run considerably fa=
ster on Cell
> > +=A0=A0=A0=A0=A0 =A0but somewhat slower on other machines. This option =
only changes
> > +=A0=A0=A0=A0=A0 =A0the scheduling of instructions, not the selection o=
f instructions
> > +=A0=A0=A0=A0=A0 =A0itself,
>=20
> It _does_ change instruction selection, which is the main factor
> in the slowdown on other machines (and a big part of the speedup
> on Cell, too). =A0It doesn't change which insns the compiler is
> allowed to use though, which is probably what you wanted to say?

Right, thanks for the correction.

	Arnd <><