From: Andi Kleen <andi@firstfloor.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Kyle McMartin <kyle@mcmartin.ca>,
tglx@linutronix.de, mingo@redhat.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: make clflush a required feature on x86_64
Date: Fri, 18 Jan 2008 15:18:39 +0100 [thread overview]
Message-ID: <20080118141839.GA16738@one.firstfloor.org> (raw)
In-Reply-To: <4790B01B.8020406@zytor.com>
On Fri, Jan 18, 2008 at 08:56:43AM -0500, H. Peter Anvin wrote:
> Andi Kleen wrote:
> >>Simulators can be fixed,
> >
> >They could, but why? I don't know of a good reason to require CLFLUSH.
>
> Well, simulators are generally expected to follow the architecture, not
> vice versa. I would tend to agree with the coupling that recent
> versions of Bochs appeared to have made here -- I think we're unlikely
> to see any processors with sse2 sans clflush, so keeping code branches
> in which will never be executed seems like a bad idea in the long term.
Here's another argument: Ingo just asked me to add a noclflush option
to the code. Guess what check that option will need?
Besides compared to the cost of a flushing clflush the branches are absolutely
in the noise.
-Andi
prev parent reply other threads:[~2008-01-18 14:15 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-18 4:59 [PATCH] x86: make clflush a required feature on x86_64 Kyle McMartin
2008-01-18 5:04 ` H. Peter Anvin
2008-01-18 5:25 ` [PATCH] x86_64: remove redundant cpu_has_ definitions Kyle McMartin
2008-01-18 8:07 ` Ingo Molnar
2008-01-18 5:53 ` [PATCH] x86: make clflush a required feature on x86_64 Andi Kleen
2008-01-18 6:01 ` Kyle McMartin
2008-01-18 6:27 ` H. Peter Anvin
2008-01-11 18:16 ` Pavel Machek
2008-01-18 6:54 ` Andi Kleen
2008-01-18 13:56 ` H. Peter Anvin
2008-01-18 14:18 ` Andi Kleen [this message]
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