From: Arjan van de Ven <arjan@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: lenb@kernel.org, rjw@rjwysocki.net, linux-acpi@vger.kernel.org,
linux-kernel@vger.kernel.org, shaohua.li@intel.com,
rui.zhang@intel.com, Mike Galbraith <bitbucket@online.de>,
Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
hpa@zytor.com
Subject: Re: [PATCH] x86, acpi, idle: Restructure the mwait idle routines
Date: Wed, 20 Nov 2013 08:24:47 -0800 [thread overview]
Message-ID: <528CE24F.5000604@linux.intel.com> (raw)
In-Reply-To: <20131120105837.GH3694@twins.programming.kicks-ass.net>
On 11/20/2013 2:58 AM, Peter Zijlstra wrote:
> On Wed, Nov 20, 2013 at 11:28:03AM +0100, Peter Zijlstra wrote:
>> On Tue, Nov 19, 2013 at 01:06:30PM -0800, Jacob Pan wrote:
>>> I applied this patch on top of upstream kernel (801a760) and found out
>>> my machine completely failed to enter idle when nothing is running.
>>> turbostate shows 100% C0. ftrace shows kernel coming in and out of idle
>>> frequently.
>>>
>>> Both ACPI idle and intel_idle behaves the same way. I have to do the
>>> following change to allow entering C-states again.
>
>> That doesn't make any sense; current_set_polling_and_test() returns the
>> same thing need_resched() does.
>>
>> But you're right, intel_idle resides 100% in C0 and acpi_idle has 100%
>> C1 residency... most weird.
>
> So pretty silly actually; you cannot do a store (any store) in between
> monitor and mwait.
you can
just not to the cacheline you are watching (or things that alias with that)
next prev parent reply other threads:[~2013-11-20 16:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-19 9:00 acpi_pad mwait usage Peter Zijlstra
2013-11-19 9:08 ` Peter Zijlstra
2013-11-19 11:31 ` [PATCH] x86, acpi, idle: Restructure the mwait idle routines Peter Zijlstra
2013-11-19 13:06 ` Rafael J. Wysocki
2013-11-19 13:21 ` Mike Galbraith
2013-11-19 14:22 ` Arjan van de Ven
2013-11-19 14:46 ` Peter Zijlstra
2013-11-19 14:51 ` Peter Zijlstra
2013-11-19 15:13 ` Peter Zijlstra
2013-11-19 21:06 ` Jacob Pan
2013-11-20 10:28 ` Peter Zijlstra
2013-11-20 10:58 ` Peter Zijlstra
2013-11-20 16:24 ` Arjan van de Ven [this message]
2013-11-20 16:33 ` Peter Zijlstra
2013-11-20 16:38 ` Arjan van de Ven
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