From: Andi Kleen <andi@firstfloor.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: Add clflush before monitor for Intel 7400 series
Date: Sat, 18 Oct 2008 09:15:39 +0200 [thread overview]
Message-ID: <87vdvqjrvo.fsf@basil.nowhere.org> (raw)
In-Reply-To: <48F91673.6090901@zytor.com> (H. Peter Anvin's message of "Fri, 17 Oct 2008 15:49:23 -0700")
"H. Peter Anvin" <hpa@zytor.com> writes:
> Pallipadi, Venkatesh wrote:
>>>>
>>> I guess I'm a bit confused about the tradeoff of CLFLUSH versus simply
>>> disabling MWAIT. This is a relatively recent processor and so
>>> optimizing matters (if this was a P4 I would be more worried about what
>>> has least impact on the kernel as a whole.)
>> As of now this is only for a limited models of CPUs (MP CPUs)
>> and not a norm. It is a errata on this CPU and not
>> something that is going to become architectural.
>>
>
> Yes, I understand. However, there is still the option to disable
> MWAIT, and the question is still open if it makes sense.
This would mean falling back to the IO port interface for deeper
C states. Even with the CLFLUSH MWAIT is a much better (and I believe
faster) interface.
-Andi
--
ak@linux.intel.com
prev parent reply other threads:[~2008-10-18 7:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-07 21:00 [PATCH] x86: Add clflush before monitor for Intel 7400 series Venki Pallipadi
2008-10-07 21:09 ` H. Peter Anvin
2008-10-07 21:49 ` Venki Pallipadi
2008-10-07 23:02 ` H. Peter Anvin
2008-10-17 20:05 ` Pallipadi, Venkatesh
2008-10-17 20:13 ` H. Peter Anvin
2008-10-17 20:51 ` Pallipadi, Venkatesh
2008-10-17 22:49 ` H. Peter Anvin
2008-10-18 7:15 ` Andi Kleen [this message]
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