Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755747Ab0FCOgn (ORCPT ); Thu, 3 Jun 2010 10:36:43 -0400 Received: from cantor2.suse.de ([195.135.220.15]:41768 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755027Ab0FCOgl (ORCPT ); Thu, 3 Jun 2010 10:36:41 -0400 Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8) From: James Bottomley To: Arve =?ISO-8859-1?Q?Hj=F8nnev=E5g?= Cc: markgross@thegnar.org, 640e9920@gmail.com, Peter Zijlstra , Brian Swetland , Ingo Molnar , LKML , Florian Mickler , Linux PM , Thomas Gleixner , Alan Cox In-Reply-To: References: <201005312338.55109.rjw@sisk.pl> <20100531232617.GF31155@gvim.org> <20100601090737.4bc243d9@schatten.dmk.lab> <20100601140519.GC1281@gvim.org> <20100602133910.GA9106@gvim.org> <20100603031842.GB11311@gvim.org> <20100603054018.GE11311@gvim.org> Content-Type: text/plain; charset="UTF-8" Date: Thu, 03 Jun 2010 09:36:34 -0500 Message-ID: <1275575794.5914.74.camel@mulgrave.site> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2924 Lines: 70 On Thu, 2010-06-03 at 00:10 -0700, Arve Hjønnevåg wrote: > On Wed, Jun 2, 2010 at 10:40 PM, mark gross <640e9920@gmail.com> wrote: > > On Wed, Jun 02, 2010 at 09:54:15PM -0700, Brian Swetland wrote: > >> On Wed, Jun 2, 2010 at 8:18 PM, mark gross <640e9920@gmail.com> wrote: > >> > On Wed, Jun 02, 2010 at 02:58:30PM -0700, Arve Hjønnevåg wrote: > >> >> > >> >> The list is not short. You have all the inactive and active > >> >> constraints on the same list. If you change it to a two level list > >> >> though, the list of unique values (which is the list you have to walk) > >> >> may be short enough for a tree to be overkill. > >> > > >> > what have you seen in practice from the wake-lock stats? > >> > > >> > I'm having a hard time seeing where you could get more than just a > >> > handfull. However; one could go to a dual list (like the scheduler) and > >> > move inactive nodes from an active to inactive list, or we could simply > >> > remove them from the list uppon inactivity. which would would well > >> > after I change the api to have the client allocate the memory for the > >> > nodes... BUT, if your moving things in and out of a list a lot, I'm not > >> > sure the break even point where changing the structure helps. > >> > > >> > We'll need to try it. > >> > > >> > I think we will almost never see more than 10 list elements. > >> > > >> > --mgross > >> > > >> > > >> > >> I see about 80 (based on the batteryinfo dump) on my Nexus One > >> (QSD8250, Android Froyo): > > > > shucks. > > > > well I think for a pm_qos class that has boolean dynamic range we can > > get away with not walking the list on every request update. we can use > > a counter, and the list will be for mostly for stats. > > > > Did you give any thought to my suggestion to only use one entry per > unique value on the first level list and then use secondary lists of > identical values. That way if you only have two constraints values the > list you have to walk when updating a request will never have more > than two entries regardless of how many total request you have. > > A request update then becomes something like this: > if on primary list { > unlink from primary list > if secondary list is not empty > get next secondary entry and add in same spot on primary list > } > unlink from secondary list > find new spot on primary list > if already there > add to secondary list > else > add to primary list This is just reinventing hash bucketed lists. To get the benefits, all we do is implement an N state constraint as backed by an N bucketed hash list, which the kernel already has all the internal mechanics for. James -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/