linux-kernel - Re: [Intel-gfx] Interrupt latency on some 945GM platforms

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Message-ID: <20100925122820.37c01ea3@gmail.com>
Date:	Sat, 25 Sep 2010 12:28:20 +0200
From:	Paolo Ornati <ornati@...il.com>
To:	Jesse Barnes <jbarnes@...tuousgeek.org>
Cc:	Vasily Khoruzhick <anarsoul@...il.com>,
	Simon Farnsworth <simon.farnsworth@...lan.co.uk>,
	intel-gfx@...ts.freedesktop.org,
	Sitsofe Wheeler <sitsofe@...oo.com>,
	Venkatesh Pallipadi <venki@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [Intel-gfx] Interrupt latency on some 945GM platforms

On Tue, 21 Sep 2010 15:56:53 -0700
Jesse Barnes <jbarnes@...tuousgeek.org> wrote:

> > I've a laptop with 945GM (Asus x5dij) and with 2.6.32+ kernels I'm
> > having random, but not frequent, screen flickering problems (for some
> > reasons 2.6.31 works fine).
> > 
> > Problem goes away with "nohz=off".
> > 
> > I'll try with "processor.max_cstate=?" and see if that works too.  
> 
> Can you guys try something like this?  My theory is that 945GM has some
> power management behavior we're failing to configure correctly.  If
> disabling it works, then it's likely related.

UPDATE: "processor.max_cstate=2" doesn't solve the sporadic flicker
problem.

The patch, applied on top of 2.6.35.4, freezes the laptop on boot.

Summary:
	nohz=off		good
	processor.max_cstate=1	good
	processor.max_cstate=2	bad

Bye,

-- 
	Paolo Ornati
	Linux 2.6.35.4 on x86_64
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