linux-kernel - Re: [PATCH] Display Intel Dynamic Acceleration feature in /proc/cpuinfo

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Message-ID: <20070524211041.GA3692@linux-os.sc.intel.com>
Date:	Thu, 24 May 2007 14:10:41 -0700
From:	Venki Pallipadi <venkatesh.pallipadi@...el.com>
To:	Dave Jones <davej@...hat.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Venki Pallipadi <venkatesh.pallipadi@...el.com>,
	Len Brown <len.brown@...el.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: [PATCH] Display Intel Dynamic Acceleration feature in /proc/cpuinfo

On Thu, May 24, 2007 at 05:01:04PM -0400, Dave Jones wrote:
> On Thu, May 24, 2007 at 01:55:13PM -0700, Andrew Morton wrote:
>  > On Wed, 23 May 2007 15:46:37 -0700
>  > Venki Pallipadi <venkatesh.pallipadi@...el.com> wrote:
>  > 
>  > > Display Intel Dynamic Acceleration feature in /proc/cpuinfo. This feature
>  > > will be enabled automatically by current acpi-cpufreq driver and cpufreq.
>  > 
>  > So you're saying that the cpufreq code in Linus's tree aleady supports IDA?
>  > If so, this is a 2.6.22 patch, isn't it?
> 
> From my limited understanding[*], ida is the "We're single threaded,
> disable the 2nd core, and clock the first core faster" magic.
> It doesn't need code-changes, as its all done in hardware afaik.

IDA state will appear as a new highest freq P-state (P0) and when software
requests that frequency, hardware can provide a higher frequency than that
oppurtunistically and transparently.

The current cpufreq code will detect this new state and enter that state
when CPU is busy.

> 
> identifying & exporting the flags on earlier kernels should be harmless,
> but not really 'mustfix'.
> 

Agree with Dave that it is not a mustfix. As the patch is pretty harmless
would be nice to have in 2.6.22.

Thanks,
Venki
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