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Date: Wed, 14 Mar 2012 13:30:57 -0700 (PDT)
From: Hugh Dickins <hughd@google.com>
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To: Daniel Lezcano <daniel.lezcano@linaro.org>
cc: Stephen Rothwell <sfr@canb.auug.org.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        Robert Lee <rob.lee@linaro.org>, Jean Pihet <j-pihet@ti.com>,
        Kevin Hilman <khilman@ti.com>,
        Deepthi Dharwar <deepthi@linux.vnet.ibm.com>,
        Dan Carpenter <dan.carpenter@oracle.com>, linux-next@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: next-20120313 cpuidle freezes when booting
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On Wed, 14 Mar 2012, Daniel Lezcano wrote:
> On 03/14/2012 08:03 PM, Hugh Dickins wrote:
> > On Wed, 14 Mar 2012, Daniel Lezcano wrote:
> > > On 03/13/2012 11:29 PM, Hugh Dickins wrote:
> > > > 
> > > > Yesterday's 3.3.0-rc7-next-20120313 gives me unpredictable freezes
> > > > on x86_64, on a ThinkPad T420s - I've not dared it on more machines.
> > > 
> > > is it possible you give the cpuidle driver your host is using ?
> > 
> > "grep IDLE .config" tells me:
> > 
> > CONFIG_ARCH_HAS_CPU_IDLE_WAIT=y
> > CONFIG_ARCH_HAS_DEFAULT_IDLE=y
> > CONFIG_CPU_IDLE=y
> > CONFIG_CPU_IDLE_GOV_LADDER=y
> > CONFIG_CPU_IDLE_GOV_MENU=y
> > CONFIG_INTEL_IDLE=y
> > # CONFIG_I7300_IDLE is not set
> > 
> > but I've a feeling that isn't what you need to know.
> 
> Thanks for these informations, I forgot to ask you for them.
> By the way, do you have CONFIG_ARCH_HAS_CPU_RELAX  ?

Yes.

> 
> > Is there some /proc or /sys file I can read to tell you?
> 
> Yes, the content of /sys/devices/system/cpu/cpuidle/current_driver

intel_idle

> and /sys/devices/system/cpu/cpuidle/current_governor_ro

menu

> 
> > Though if it's something that changes dynamically, then what
> > I read now might not be what it would say when things go wrong.
> 
> No, that won't change, so the information should be enough for me to find the
> code path where the regression is.
> 
> > I expect you've realized by now, I haven't a clue about cpuidle
> > drivers: I hadn't even realized that idleness needs a driver.
> 
> No problem, thanks for git bisecting and find the culprit :)

Thank you - let me know if you've something you'd like me to try.

Hugh