Message-Id: <200809051308.14079.rjw@sisk.pl>
Date:	Fri, 5 Sep 2008 13:08:13 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Anders Aagaard <aagaande@...il.com>
Cc:	suspend-devel@...ts.sourceforge.net,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [Suspend-devel] Resume performance

On Friday, 5 of September 2008, Anders Aagaard wrote:
> Hi

Hi,

This is a kernel problem, so let's CC the LKML.

> I have a intel P35 board with a quad core cpu in it, it's currently 
> running as a server for a small network, and I'd like to be able to shut 
> it down when idle, and use wake on lan to wake it up when it's needed. 
> Now I got that part working quite well, but for some reason I have a 
> long delay in resume.
> 
> I seem to remember being able to resume this computer in 2-3 seconds 
> when I was testing it, now it needs 35 seconds to resume.  It seems 
> regardless of resume options used, and it always resumes to a working 
> state without problems.

What kernel are you using at the moment and which one was used for the
testing?

> I've tried quite a lot of things, booting with noapic/nosmp, booting a 
> kernel without usb/network drivers, disabling ahci (using ata_piix 
> driver instead of ahci), and there's always that one long delay.  And 
> I'm not quite sure how the kernel printk timing information works, so 
> I'm not sure whats causing that delay.
> 
> Output from dmesg when booting with nosmp (to get accurate timing data):
> scripts/show_delta -b "Force enabled HPET at resume"
> [349.821150 < 7.039261 >] ata3.00: configured for UDMA/133
> [349.821160 < 7.039271 >] sd 2:0:0:0: [sdc] 976773168 512-byte hardware 
> sectors (500108 MB)
> [349.821165 < 7.039276 >] sd 2:0:0:0: [sdc] Write Protect is off
> [349.821166 < 7.039277 >] sd 2:0:0:0: [sdc] Mode Sense: 00 3a 00 00
> [349.821173 < 7.039284 >] sd 2:0:0:0: [sdc] Write cache: enabled, read 
> cache: enabled, doesn't support DPO or FUA
> [349.972801 < 7.190912 >] ata1: SATA link up 3.0 Gbps (SStatus 123 
> SControl 300)
> [349.979060 < 7.197171 >] ata1.00: configured for UDMA/133
> [349.979070 < 7.197181 >] sd 0:0:0:0: [sda] 976771055 512-byte hardware 
> sectors (500107 MB)
> [349.979075 < 7.197186 >] sd 0:0:0:0: [sda] Write Protect is off
> [349.979076 < 7.197187 >] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00
> [349.979083 < 7.197194 >] sd 0:0:0:0: [sda] Write cache: enabled, read 
> cache: enabled, doesn't support DPO or FUA

It looks like this happens here.  Can you try to unload the network driver
before suspend, please?

> [373.945179 < 31.163290 >] r8169: eth0: link up
> [373.952159 < 31.170270 >] PM: Writing back config space on device 
> 0000:02:02.0 at offset f (was 4020100, writing 4020104)
> [373.952172 < 31.170283 >] PM: Writing back config space on device 
> 0000:02:02.0 at offset 5 (was 0, writing fddf8000)
> [373.952176 < 31.170287 >] PM: Writing back config space on device 
> 0000:02:02.0 at offset 4 (was 0, writing fddfd000)
> [373.952180 < 31.170291 >] PM: Writing back config space on device 
> 0000:02:02.0 at offset 3 (was 0, writing 4410)
> [373.952185 < 31.170296 >] PM: Writing back config space on device 
> 0000:02:02.0 at offset 1 (was 2100000, writing 2100006)
> 
> Notice the long delay between all hd's found and it writing back config 
> space, note that this happens with or without that network card driver 
> in the kernel.
> 
> Attaching full log of boot + suspend/resume cycle, kernel booted with 
> nosmp/noapic, it takes the same amount of time without those options, 
> but timing data gets a bit garbled.
> 
> Thanks for your work so far, it's working quite well and saving me a lot 
> of power doing it this way, at this point I'm just trying to get it 
> faster :)

Sure, 35 seconds to resume is hardly acceptable.

Thanks,
Rafael
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