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Message-ID: <87vdvqjrvo.fsf@basil.nowhere.org> Date: Sat, 18 Oct 2008 09:15:39 +0200 From: Andi Kleen <andi@...stfloor.org> To: "H. Peter Anvin" <hpa@...or.com> Cc: "Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>, Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>, linux-kernel <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] x86: Add clflush before monitor for Intel 7400 series "H. Peter Anvin" <hpa@...or.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@...ux.intel.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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