Date: Mon, 25 Sep 2006 17:22:40 -0700
From: Andrew Morton <akpm@osdl.org>
To: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <ncunningham@linuxmail.org>,
       Stefan Seyfried <seife@suse.de>, linux-kernel@vger.kernel.org,
       "Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: When will the lunacy end? (Was Re: [PATCH] uswsusp: add
 pmops->{prepare,enter,finish} support (aka "platform mode"))
Message-Id: <20060925172240.5c389c25.akpm@osdl.org>
In-Reply-To: <20060925232151.GA1896@elf.ucw.cz>
References: <20060925071338.GD9869@suse.de>
	<1159220043.12814.30.camel@nigel.suspend2.net>
	<20060925144558.878c5374.akpm@osdl.org>
	<20060925224500.GB2540@elf.ucw.cz>
	<20060925160648.de96b6fa.akpm@osdl.org>
	<20060925232151.GA1896@elf.ucw.cz>
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On Tue, 26 Sep 2006 01:21:51 +0200
Pavel Machek <pavel@ucw.cz> wrote:

> Hi!
> 
> On Mon 2006-09-25 16:06:48, Andrew Morton wrote:
> > On Tue, 26 Sep 2006 00:45:00 +0200
> > Pavel Machek <pavel@ucw.cz> wrote:
> > 
> > > Anyways this boils down to "find which drivers are delaying suspend
> > > and fix them".
> > 
> > The first step would be "find some way of identifying where all the time is
> > being spent".
> > 
> > Right now, netconsole gets disabled (or makes the machine hang) and most of
> > these machines don't have serial ports and the printk buffer gets lost
> > during resume.
> > 
> > The net result is that the machine takes a long time to suspend and resume,
> > and you don't have a clue *why*.
> > 
> > And this is a significant issue, IMO.  In terms of
> > niceness-of-user-interface, being able to suspend in twelve seconds instead
> > of twenty seven rates fairly highly...
> 
> Your machines spend 15 seconds in drivers? Ouch, I did not realize
> _that_. 
> 
> (My machine suspends in 7 seconds, perhaps 2-3 of that are playing
> with drivers, so I just failed to see where the problem is).
> 
> Are these your big SMP servers? Any SCSI involved?

It's my long-suffering Vaio laptop.

> Rafael has "fakesuspend" patches somewhere, but you can probably just
> swapoff -a, then echo disk > /sys/power/state. If you are lucky, that
> should be slow, too... fortunately you'll have useful dmesg buffer
> when you are done. CONFIG_PRINTK_TIMING or something, and you should
> have enough clues...?

That would help.

> 15 seconds spend within drivers is definitely _not_ okay.

I assumed it was the same for everyone else ;)
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