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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [patch 3/3] cell: prevent alignment interrupt on local store
Date: Thu, 12 Apr 2007 08:50:27 +0200
To: Olaf Hering <olaf@aepfle.de>
Cc: Arnd Bergmann <arnd@arndb.de>, Akinobu Mita <mita@fixstars.com>,
	linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
	cbe-oss-dev@ozlabs.org
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>> This isn't just a kernel issue either; the same holds
>> for all of userspace.  It seems to me the only way to
>> get good performance on both Cell and all other platforms
>> is to have a separate binary distribution for Cell.
>
> How much will this impact performance on a 970, 74xx or POWER6 if
> everything gets compiled with '--mcpu=$cell', compared to what is used
> today? One gets at least altivec that way.

Can't comment on POWER6; but on 74xx or 970 it will
hurt.  A lot.  Say 20-%30% or so?  [Yes I have no
benchmark data to back this up].


Segher