linux-kernel - Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 16 Dec 2009 20:27:16 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Zhang Rui <rui.zhang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems)

On Wednesday 16 December 2009, Linus Torvalds wrote:
> 
> On Wed, 16 Dec 2009, Rafael J. Wysocki wrote:
> > 
> > The summarized data are below (the "big" numbers are averages and the +/-
> > numbers are standard deviations, all in milliseconds):
> > 
> > 			HP nx6325		MSI Wind U100
> > 
> > sync suspend		1482 (+/- 40)	1180 (+/- 24)
> > sync resume		2955 (+/- 2)	3597 (+/- 25)
> > 
> > async suspend		1553 (+/- 49)	1177 (+/- 32)
> > async resume		2692 (+/- 326)	3556  (+/- 33)
> > 
> > async+one-liner suspend	1600 (+/- 39)	1212 (+/- 41)
> > async+one-liner resume	2692 (+/- 324)	3579 (+/- 24)
> > 
> > async+extra suspend	1496 (+/- 37)	1217 (+/- 38)
> > async+extra resume	1859 (+/- 114)	1923 (+/- 35)
> > 
> > So, in my opinion, with the above set of "async" devices, it doesn't
> > make sense to do async suspend at all, because the sync suspend is actually
> > the fastest on both machines.
> 
> Hmm. I certainly agree - your numbers do not seem to support any async at 
> all.
> 
> However, I do note that for the "extra patch" makes a big difference at 
> resume time. That implies that the resume serializes on some slow device 
> that wasn't marked async - and starting the async ones early avoids that. 
> 
> But without the per-device timings, it's hard to even guess what device 
> that was.
> 
> But even that doesn't really help the suspend cases, only resume.
> 
> Do you have any sample timing output with devices listed?

I'm going to generate one shortly.

Rafael
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/