From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [PATCH 2/6] PM: Asynchronous resume of devices Date: Sun, 30 Aug 2009 15:09:50 +0200 Message-ID: <200908301509.50855.rjw@sisk.pl> References: <200908291449.57667.rjw@sisk.pl> <20090830064533.GA1417@ucw.cz> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090830064533.GA1417@ucw.cz> Sender: linux-pci-owner@vger.kernel.org To: Pavel Machek Cc: Alan Stern , linux-pm , LKML , Len Brown , ACPI Devel Maling List , Arjan van de Ven , Zhang Rui , Dmitry Torokhov , Linux PCI List-Id: linux-acpi@vger.kernel.org On Sunday 30 August 2009, Pavel Machek wrote: > Hi! > > > > > > > > The same goes for the noirq versions. > > > > > > > > > > > > I thought about that, but there are a few things to figure out: > > > > > > - how many threads to start > > > > > > > > > > That's a tough question. Right now you start roughly as many threads > > > > > as there are async devices. That seems like overkill. > > > > > > > > In fact they are substantially fewer than that, for the following reasons. > > > > > > > > First, the async framework will not start more than MAX_THREADS threads, > > > > which is 256 at the moment. This number is less than the number of async > > > > devices to handle on an average system. > > > > > > Okay, but MAX_THREADS isn't under your control. Remember also that > > > each thread takes up some memory, and during hibernation we are in a > > > memory-constrained situation. > > > > We keep some extra free memory for things like this. It's not likely to be > > exhausted by the async threads alone. > > What extra memory? You are creating quite a lot of threads. For 256 of > them, it would take cca 2MB... We never start that many threads and even if there's not enough memory to start a new thread, the async framework will handle that for us. > You recently removed code from s2disk that freed 4MB of extra memory, That was removed from s2ram. For STD we still have PAGES_FOR_IO and SPARE_PAGES, nothing's changed there. Thanks, Rafael