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From: Pavel Machek <pavel@ucw.cz>
To: Jim Gettys <jg@laptop.org>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	"Brown, Len" <len.brown@intel.com>,
	Linux Kernel ML <linux-kernel@vger.kernel.org>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	ACPI ML <linux-acpi@vger.kernel.org>,
	Adam Belay <abelay@novell.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>,
	devel@laptop.org
Subject: Re: [OLPC-devel] Re: [RFC][PATCH 1/2] ACPI: Idle Processor PM Improvements
Date: Mon, 4 Sep 2006 13:09:33 +0000	[thread overview]
Message-ID: <20060904130933.GC6279@ucw.cz> (raw)
In-Reply-To: <1157070616.7974.232.camel@localhost.localdomain>

Hi!

> In short, we have novel hardware: we can have our screen on, and suspend
> the processor to RAM, and use a half a watt.  We can have our wireless
> forwarding packets in our mesh networks, with the processor suspended,
> consuming under 400mw (we hope 300mw by the time we ship).  Both on, and
> we're still under one watt.
> 
> For keyboard activity, human perception is in the 100-200 millisecond
> range; for some other stuff, it is even less much than that.  So that's
> the necessity; now the invention.
> 
> I've done a straw pole among kernel gurus at OLS and elsewhere on how
> fast Linux might be able to resume. I've gotten answers of typically
> "one second".
> 
> But, on other platforms (see attached), I have data I've measured myself
> showing Linux going from resume from RAM to *scheduling user level
> processes* 100 times faster than that, on a wimpy 200mhz ARM processor.
> Yes, Matilda, Linux can, on non-braindead hardware, resume all the way
> to scheduling user processes in 10 milliseconds on a 200mhz processor.

2.4 and 2.6 are *very* different here. You'll probably need to optimize freezer
in 2.6 a bit...
							Pavel
-- 
Thanks for all the (sleeping) penguins.

  parent reply	other threads:[~2006-09-04 13:09 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-30 18:40 Pallipadi, Venkatesh
2006-08-30 19:43 ` Matthew Garrett
2006-08-31 23:13   ` Bjorn Helgaas
2006-09-01  0:30     ` [OLPC-devel] " Jim Gettys
2006-09-01  3:53       ` Len Brown
2006-09-01  4:12         ` Matthew Garrett
2006-09-01 15:51           ` Jordan Crouse
2006-09-01 13:14         ` [OLPC-devel] Re: [RFC][PATCH 1/2] " Carl-Daniel Hailfinger
2006-09-01 21:52         ` Andi Kleen
2006-09-01 22:57           ` Alan Cox
2006-09-04 13:13         ` Pavel Machek
2006-09-04 13:09       ` Pavel Machek [this message]
2006-09-05 14:31         ` Jim Gettys
2006-09-06 10:37           ` Pavel Machek
2006-09-06 14:58             ` Jordan Crouse
2006-09-12  9:21               ` Pavel Machek
2006-09-12 18:14                 ` Jim Gettys
2006-09-12 18:27                   ` Mitch Bradley
2006-09-12 20:18                   ` Jordan Crouse
2006-09-14  9:20                     ` Pavel Machek
2006-09-14  9:18                   ` Pavel Machek
2006-09-14 11:29                     ` Jim Gettys
2006-09-06 15:19             ` [OLPC-devel] Re: [RFC][PATCH 1/2] " Jim Gettys
2006-09-12  9:21               ` Pavel Machek

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