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Date: Thu, 5 Aug 2010 07:23:04 -0700
Message-ID: <AANLkTikJH=t-67TAeUjgWM1=B86ZKq1b1V4WKHHgrfuH@mail.gmail.com>
Subject: Re: Attempted summary of suspend-blockers LKML thread
From: Brian Swetland <swetland@google.com>
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: david@lang.hm, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        "Rafael J. Wysocki" <rjw@sisk.pl>,
        Arjan van de Ven <arjan@infradead.org>,
        linux-pm@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        pavel@ucw.cz, florian@mickler.org, stern@rowland.harvard.edu,
        peterz@infradead.org, tglx@linutronix.de, alan@lxorguk.ukuu.org.uk
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On Thu, Aug 5, 2010 at 7:16 AM, Matthew Garrett <mjg59@srcf.ucam.org> wrote:
> On Thu, Aug 05, 2010 at 07:07:06AM -0700, david@lang.hm wrote:
>> On Thu, 5 Aug 2010, Matthew Garrett wrote:
>>> The decision on whether or not to go to sleep isn't the difficult bit of
>>> this problem space.
>>
>> but isn't that all that wakelocks do? affect the decision on whether or
>> not to go to sleep.
>
> You could think of them that way, but it's not the useful aspect of them
> - that much could be implemented entirely in userspace. Wakelocks
> provide a mechanism for userspace to ensure that it's handled all
> received events before a system suspend takes place.

For userspace or the kernel -- some events may not require userspace
intervention, but do require the kernel to stay awake long enough to
finish chewing on them.  Say perhaps a wifi irq comes in, the wifi
driver/stack needs to process some beacon packets or whatnot.

Brian
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