linux-kernel - Re: strange keyboard lag after suspend testing

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Message-ID: <20070321222216.GG6057@elf.ucw.cz>
Date:	Wed, 21 Mar 2007 23:22:16 +0100
From:	Pavel Machek <pavel@....cz>
To:	Luca Tettamanti <kronos.it@...il.com>
Cc:	Andreas Mohr <andi@...x01.fht-esslingen.de>, vojtech@...e.cz,
	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: strange keyboard lag after suspend testing

Hi!

> >> > >No, it is not keyboard rate. Keyboard lags during normal typing,
> >> > >sometimes letters come in groups of two or so...
> >> > 
> >> > I might start looking at embedded controller changes and switches. If
> >> > ACPI misbehaves that could starve keyboard controller... But you
> >> > said
> >> 
> >> Mouse _seems_ okay, but I'm not sure if I'd notice lag there.
> >> 
> >> > that mouse is OK... Hmm, what happens if you load evbug and type while
> >> > watching syslog. Do you observe the same delays?
> >> 
> >> Hmm, seems that it only happens in X... so maybe it is some strange
> >> scheduling artefact?
> >> 
> >> Hmm, something is wrong here:
> >> 
> >> On console, I get expected 4-5 ticks a second. In x in gnome-terminal,
> >> I get this:
> > 
> > It gets weirder: I killed some tasks and now: (on unloaded system
> > running X, notice that top latency was ~1sec at 33:09).
> > 
> > root@amd:~# while true ; do echo -n . ; sleep .2; date; done
> > .Tue Mar 20 17:33:07 CET 2007
> > .Tue Mar 20 17:33:07 CET 2007
> > .Tue Mar 20 17:33:08 CET 2007
> > .Tue Mar 20 17:33:08 CET 2007
> > .Tue Mar 20 17:33:08 CET 2007
> > .Tue Mar 20 17:33:08 CET 2007
> > .Tue Mar 20 17:33:09 CET 2007
> > .Tue Mar 20 17:33:10 CET 2007
> > .Tue Mar 20 17:33:10 CET 2007
> > .Tue Mar 20 17:33:10 CET 2007
> > .Tue Mar 20 17:33:10 CET 2007
> > .Tue Mar 20 17:33:10 CET 2007
> > .Tue Mar 20 17:33:11 CET 2007
> > .Tue Mar 20 17:33:11 CET 2007
> > .Tue Mar 20 17:33:11 CET 2007
> > .Tue Mar 20 17:33:12 CET 2007
> > .Tue Mar 20 17:33:12 CET 2007
> > 
> > As soon as I load the cpu up with while1, machine starts to behave.
> > 
> > When I turn on bluetooth (USB), ACPI can no longer use C3, and machine
> > starts to behave. Hmm?
> 
> When the CPU is in C3 the TSC and LAPIC (IIRC) are stopped, sounds like
> the problem is here. Maybe after resume kernel fails to fall back to a
> "safe" clocksource.

Notice that problem is _not_ easily reproducible :-(. One suspend is
not enough to trigger it.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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