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 07:47:43 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
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 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?

			Linus
--
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/