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Date: Sun, 14 Dec 2003 17:54:36 +0100
From: Arjan van de Ven <arjanv@redhat.com>
To: Andi Kleen <ak@suse.de>
Cc: Arjan van de Ven <arjanv@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [CFT][RFC] HT scheduler
Message-ID: <20031214165435.GA10326@devserv.devel.redhat.com>
References: <20031213022038.300B22C2C1@lists.samba.org.suse.lists.linux.kernel> <3FDAB517.4000309@cyberone.com.au.suse.lists.linux.kernel> <brgeo7$huv$1@gatekeeper.tmr.com.suse.lists.linux.kernel> <3FDBC876.3020603@cyberone.com.au.suse.lists.linux.kernel> <20031214043245.GC21241@mail.shareable.org.suse.lists.linux.kernel> <3FDC3023.9030708@cyberone.com.au.suse.lists.linux.kernel> <1071398761.5233.1.camel@laptop.fenrus.com.suse.lists.linux.kernel> <p73ad5vs6vk.fsf@verdi.suse.de>
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On Sun, Dec 14, 2003 at 05:26:23PM +0100, Andi Kleen wrote:
> Arjan van de Ven <arjanv@redhat.com> writes:
> > 
> > also keep in mind that current x86 processors all will internally
> > optimize out the lock prefix in UP mode or when the cacheline is owned
> > exclusive.... If HT matters here let the cpu optimize it out.....
> 
> Are you sure they optimize it out in UP mode? IMHO this would break
> device drivers that use locked cycles to communicate with bus master
> devices (and which are not necessarily mapped uncachable/write combining) 

uncachable regions are different obviously....