From: Arjan van de Ven <arjan@linux.intel.com>
To: Colin Cross <ccross@android.com>
Cc: Kevin Hilman <khilman@ti.com>, Len Brown <len.brown@intel.com>,
linux-kernel@vger.kernel.org,
Amit Kucheria <amit.kucheria@linaro.org>,
linux-tegra@vger.kernel.org, linux-pm@lists.linux-foundation.org,
linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/3] coupled cpuidle state support
Date: Wed, 21 Dec 2011 10:44:42 +0100 [thread overview]
Message-ID: <4EF1AA8A.8060304@linux.intel.com> (raw)
In-Reply-To: <CAMbhsRRP7s9xsHqxhb=iMfHAJFcqAea-6CDORZS34RCPNo+UWw@mail.gmail.com>
On 12/21/2011 10:40 AM, Colin Cross wrote:
>> this smells fundamentally racey to me; you can get an interrupt one
>> cycle after you think you're done, but before the last guy enters WFI...
>>
>> how do you solve that issue ?
>
> All the cpus have interrupts off when they increment the counter, so
> they cannot receive an interrupt. If an interrupt is pending on one
> of those cpus, it will be handled later when WFI aborts due to the
> pending interrupt.
... but this leads to cases where you're aborting before other cpus are
entering..... so your "last guy in" doesn't really work, since while cpu
0 thinks it's the last guy, cpu 1 is already on the way out/out
already... (heck it might already be going back to sleep if your idle
code can run fast, like in the size of a cache miss)
next prev parent reply other threads:[~2011-12-21 9:44 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-21 0:09 [PATCH 0/3] coupled cpuidle state support Colin Cross
2011-12-21 0:09 ` [PATCH 1/3] cpuidle: refactor out cpuidle_enter_state Colin Cross
2012-01-04 14:08 ` Jean Pihet
[not found] ` <1324426147-16735-1-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2011-12-21 0:09 ` [PATCH 2/3] cpuidle: fix error handling in __cpuidle_register_device Colin Cross
2011-12-21 0:09 ` [PATCH 3/3] cpuidle: add support for states that affect multiple cpus Colin Cross
2011-12-21 9:02 ` [PATCH 0/3] coupled cpuidle state support Arjan van de Ven
[not found] ` <4EF1A0B4.5080307-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2011-12-21 9:40 ` Colin Cross
2011-12-21 9:44 ` Arjan van de Ven [this message]
[not found] ` <4EF1AA8A.8060304-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2011-12-21 9:55 ` Colin Cross
2011-12-21 12:12 ` Arjan van de Ven
2011-12-21 19:05 ` Colin Cross
[not found] ` <CAMbhsRRnKoR3YPWrZzVynVe+dcuU5v0siYvmp2vbBcS1hquC7Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-21 19:36 ` Arjan van de Ven
2011-12-21 19:42 ` Colin Cross
[not found] ` <CAMbhsRSPCo9MSGp57Fv0sRdYUFcdwx8jEz1-CfX8LdKf8X4MVg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2011-12-22 8:35 ` [linux-pm] " Shilimkar, Santosh
2011-12-22 8:53 ` Arjan van de Ven
2011-12-22 9:30 ` [linux-pm] " Shilimkar, Santosh
[not found] ` <4EF2F01E.8060307-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2011-12-22 21:20 ` Colin Cross
[not found] ` <4EF1CD49.9020800-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2012-03-14 0:39 ` Colin Cross
2012-01-04 0:41 ` Kevin Hilman
2012-01-04 17:27 ` Shilimkar, Santosh
2012-01-20 8:46 ` Daniel Lezcano
2012-01-20 20:40 ` Colin Cross
2012-01-25 14:04 ` Daniel Lezcano
2012-01-31 14:13 ` Daniel Lezcano
[not found] ` <CAMbhsRTbVqV6p0py9NGZrpFPf2yvp-B0dr+o-m7qbdja_-Lfzw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-01-27 8:54 ` [linux-pm] " Vincent Guittot
2012-01-27 17:32 ` Colin Cross
[not found] ` <CAMbhsRQYVXTZ2pX4mBrM6=SyGTqn_GY8xsW4rt_e21zerEzctA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-02-01 12:13 ` Vincent Guittot
2012-02-01 14:59 ` Lorenzo Pieralisi
2012-02-01 17:30 ` [linux-pm] " Colin Cross
2012-02-01 18:07 ` Lorenzo Pieralisi
2012-02-03 1:19 ` Colin Cross
2012-03-13 23:52 ` Kevin Hilman
[not found] ` <8762e8kqi6.fsf-l0cyMroinI0@public.gmane.org>
2012-03-14 0:28 ` Colin Cross
2012-03-14 0:47 ` Colin Cross
[not found] ` <CAMbhsRRD2bdkcUZvScb-cF05e=R3h69bNVaTPFX4jBKBBOjuMg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-03-14 14:23 ` [linux-pm] " Kevin Hilman
2012-03-14 2:04 ` Arjan van de Ven
2012-03-14 2:21 ` Colin Cross
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