linux-kernel - Re: [BUG] Strange 1-second pauses during Resume-from-RAM

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Message-ID: <20071201151650.GA5031@lazybastard.org>
Date:	Sat, 1 Dec 2007 16:16:50 +0100
From:	Jörn Engel <joern@...fs.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Jörn Engel <joern@...fs.org>,
	Mark Lord <lkml@....ca>, Pavel Machek <pavel@....cz>,
	Mark Lord <liml@....ca>, Thomas Gleixner <tglx@...utronix.de>,
	len.brown@...el.com, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-pm@...ts.linux-foundation.org,
	rjw@...k.pl
Subject: Re: [BUG] Strange 1-second pauses during Resume-from-RAM

On Fri, 30 November 2007 19:46:25 +0100, Ingo Molnar wrote:
> * Jörn Engel <joern@...fs.org> wrote:
> > 
> > It compiles.  It boots with a 512M RAM (384M was too little with all
> > the other debug options on).  But it seems to lock up when running
> > trace-cmd.  On a rerun it locks up again, but with different output.
> 
> hm, you should decrease MAX_TRACE in kernel/latency_tracing.c from 1 
> million to 16K or so. 1 million entries probably depletes lowmem quite 
> seriously.

That's ok.  RAM is cheap.

> > Rerun was captured:
> > http://logfs.org/~joern/trace1.jpg
> 
> hm, that looks weird. if you disable CONFIG_PROVE_LOCKING, does that 
> improve things? (or just turns a noisy lockup into a silent lockup?)

Not much, although the dumps look different now:
http://logfs.org/~joern/trace3.jpg
http://logfs.org/~joern/trace4.jpg

I have to change my qemu setup a little to see the top of those
dumps...

> > I should do a couple of runs, but my girlfriend claims realtime 
> > priority for the evening.
> 
> yeah, SCHED_IDLE is not generally well received by them.

...as soon as more urgent tasks has finished (weekend is over).

Jörn

-- 
It does not matter how slowly you go, so long as you do not stop.
-- Confucius
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