From: Arnd Bergmann <arnd@arndb.de>
To: David Woodhouse <dwmw2@infradead.org>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH] add Kconfig option for optimizing for cell
Date: Sat, 15 Sep 2007 15:30:15 +0200 [thread overview]
Message-ID: <200709151530.15441.arnd@arndb.de> (raw)
In-Reply-To: <1189862035.3742.5.camel@shinybook.infradead.org>
On Saturday 15 September 2007, David Woodhouse wrote:
> On Sat, 2007-09-15 at 02:21 +0200, Arnd Bergmann wrote:
> > Since the PPE on cell is an in-order core, it suffers significantly
> > from wrong instruction scheduling. This adds an Kconfig option that
> > enables passing -mtune=cell to gcc in order to generate object
> > code that runs well on cell.
>
> Do we have an option which is useful for a multiplatform kernel (and for
> userspace) and which lies between the two extremes? Something which will
> improve performance on Cell (and POWER6?) without sucking too hard
> elsewhere?
No, not really. The impact of -mtune=cell should not be too bad on other
out-of-order CPUs, but we don't have any good measurements to back that
up, and it may also be really bad for POWER6 and other in-order cores.
Arnd <><
prev parent reply other threads:[~2007-09-15 13:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-15 0:21 [PATCH] add Kconfig option for optimizing for cell Arnd Bergmann
2007-09-14 23:07 ` Josh Boyer
2007-09-15 1:02 ` Arnd Bergmann
2007-09-14 23:36 ` Josh Boyer
2007-09-15 0:50 ` Segher Boessenkool
2007-09-15 1:02 ` Arnd Bergmann
2007-09-15 13:13 ` David Woodhouse
2007-09-15 13:30 ` Arnd Bergmann [this message]
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