linux-kernel - Re: [linux-pm] sleepy linux self-test

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Message-ID: <20080210210349.GI15662@elf.ucw.cz>
Date:	Sun, 10 Feb 2008 22:03:49 +0100
From:	Pavel Machek <pavel@....cz>
To:	David Brownell <david-b@...bell.net>
Cc:	rjw@...k.pl, mingo@...e.hu, linux-pm@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [linux-pm] sleepy linux self-test

Hi!

> > > > The changes look good to me.
> > > 
> > > They feel unfinished to me though.  :)
> > > 
> > > Like using "jiffies" instead of a clocksource, which makes trouble
> > > since the timing covers periods with IRQs disabled.  And the test
> > > mode parameter needs work.
> >
> > Well, I'd say that timing has bigger problem, right?
> >
> > It is
> >
> > set alarm
> > 	suspend system
> > | poweroff
> > alarm expires
> > 	system resumes
> >
> > ... so you are measuring resume time + sleep time, no? 
> 
> There's no "poweroff" step when entering STR or STANDBY!
> 
> But more specifically, I avoided that issue by comparing times between
>   (a) start and end of the "suspend devices" steps;
>   (b) start and end of the "resume devices" steps.
> 
> Example output, with the relevant lines highlighted by "*":
> 
>     PM: test RTC wakeup from 'mem' suspend
>     PM: Syncing filesystems ... done.
>     PM: Preparing system for mem sleep
>     Freezing user space processes ... (elapsed 0.00 seconds) done.
>     Freezing remaining freezable tasks ... (elapsed 0.00 seconds) done.
>     PM: Entering mem sleep
>     Suspending console(s)
>  *  PM: suspend devices took 0.000 seconds
>     GPIO-A may wake for 00080000
>     GPIO-C may wake for 00000008
>     GPIO-D may wake for 00000020
>     AT91: PM - wake mask 00000036, pm state 3
>     AT91: PM - no slow clock mode yet ...
>     AT91: PM - wakeup 00000002
>  *  PM: resume devices took 0.132 seconds
>     PM: Finishing wakeup.
>     Restarting tasks ... done.
> 
> The underlying clocksource has resolution of 32 KiHz, while HZ=128;
> the "suspend" more typically reports 7 msec.  And there should be a
> few more wakeup GPIOs, except I seem to not have enabled gpio_keys.
> That "wakeup 00000002" means the heavily-overloaded "system" IRQ
> woke the system ... the RTC is on that IRQ line.

Aha, that should work, yes. Sorry for noise.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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