From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Walker Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 6) Date: Thu, 13 May 2010 13:36:20 -0700 Message-ID: <1273782980.19100.96.camel@c-dwalke-linux.qualcomm.com> References: <20100513191717.GA3428@atomide.com> <20100513192522.GA19256@srcf.ucam.org> <20100513194205.GC3428@atomide.com> <20100513195349.GB19722@srcf.ucam.org> <20100513200003.GE3428@atomide.com> <20100513200814.GA20254@srcf.ucam.org> <20100513202320.GF3428@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from fifo99.com ([67.223.236.141]:60771 "EHLO fifo99.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756577Ab0EMUgc (ORCPT ); Thu, 13 May 2010 16:36:32 -0400 In-Reply-To: <20100513202320.GF3428@atomide.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Tony Lindgren Cc: Matthew Garrett , Alan Stern , Paul Walmsley , Arve =?ISO-8859-1?Q?Hj=F8nnev=E5g?= , Linux-pm mailing list , Kernel development list , Tejun Heo , Oleg Nesterov , Kevin Hilman , magnus.damm@gmail.com, Theodore Ts'o , mark gross , Arjan van de Ven , Geoff Smith , Brian Swetland , "Rafael J. Wysocki" , =?ISO-8859-1?Q?Beno=EEt?= Cousson , linux-omap@vger.kernel.org, Vitaly Wool , Mark Brown , Liam Girdwood On Thu, 2010-05-13 at 13:23 -0700, Tony Lindgren wrote: > * Matthew Garrett [100513 13:03]: > > On Thu, May 13, 2010 at 01:00:04PM -0700, Tony Lindgren wrote: > > > > > The system stays running because there's something to do. The system > > > won't suspend until all the processors hit the kernel idle loop and > > > the next_timer_interrupt_critical() returns nothing. > > > > At which point an application in a busy loop cripples you. > > Maybe you could deal with the misbehaving untrusted apps in the userspace > by sending kill -STOP to them when the screen blanks? Then continue > when some event wakes up the system again. Couldn't you just use priorities (nice), or cgroups to deal with that? I'm sure there is a way to limit an apps runtime, so the system does go idle sometimes. > > I think we could implement your suggestion more easily by just giving > > untrusted applications an effectively infinite amount of timer slack, > > but it still doesn't handle the case where an app behaves excrutiatingly > > badly. > > Hmm, if you use timer slack then you still need to search through > the whole timer list instead of a smaller critical timer list. > Both ways sound doable though. There are deferrable timers already in Linux.. It seems like it would just be an extension of that. Daniel