From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753515AbbJSK6H (ORCPT ); Mon, 19 Oct 2015 06:58:07 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:34029 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbbJSK6C (ORCPT ); Mon, 19 Oct 2015 06:58:02 -0400 Subject: Re: [PATCH 04/14] init: deps: order network interfaces by link order To: Greg Kroah-Hartman References: <5622956F.80408@ahsoftware.de> <56229B0B.80100@ahsoftware.de> <56229E1A.8010803@ahsoftware.de> <20151017193606.GA2315@kroah.com> <5623272A.1050205@ahsoftware.de> <20151018051443.GA29830@kroah.com> <56232C22.4030502@ahsoftware.de> <20151018055926.GB31909@kroah.com> <56237061.1030006@ahsoftware.de> Cc: Linux Kernel Mailing List , Andrew Morton , Russell King , Grant Likely From: Alexander Holler Message-ID: <5624CCAF.6050404@ahsoftware.de> Date: Mon, 19 Oct 2015 12:57:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <56237061.1030006@ahsoftware.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 18.10.2015 um 12:11 schrieb Alexander Holler: > Am 18.10.2015 um 07:59 schrieb Greg Kroah-Hartman: >> On Sun, Oct 18, 2015 at 07:20:34AM +0200, Alexander Holler wrote: >>> Am 18.10.2015 um 07:14 schrieb Greg Kroah-Hartman: >>>> On Sun, Oct 18, 2015 at 06:59:22AM +0200, Alexander Holler wrote: >>>>> Am 17.10.2015 um 21:36 schrieb Greg Kroah-Hartman: >>>>> >>>>>> Again, parallelizing does not solve anything, and causes more >>>>>> problems >>>>>> _and_ makes things take longer. Try it, we have done it in the >>>>>> past and >>>>>> proven this, it's pretty easy to test :) >>>>> >>>>> Just because I'm curious, may I ask how I would test that in the >>>>> easy way >>>>> you have in mind? I've just posted the results of my tests (the patch >>>>> series) but I wonder what you do have in mind. >>>> >>>> Use the tool, scripts/bootgraph.pl to create a boot graph of your boot >>>> sequence. That should show you the drivers, or other areas, that are >>>> causing your boot to be "slow". >>> >>> So I've misunderstood you. I've read your paragraph as that it's easy to >>> test parallelizing. >> >> Ah, ok, if you want to parallelize everything, add some logic in the >> driver core where the probe() callback is made to spin that off into a >> new thread for every call, and when it's done, clean up the thread. >> That's what I did many years ago to try this all out, if you dig in the >> lkml archives there's probably a patch somewhere that you can base the >> work off of to test it yourself. > > Hmm, I don't think I will do that because that means to setup a new > thread for every call. And it doesn't need much imagination (or > experience) that this introduces quite some overhead. > > But maybe it makes sense to try out what I'm doing in my patches, > starting multiple threads once and then just giving them some work. Will After a having second thought on your simple approach to parallelize stuff, I have to say that it just can't work because just starting a thread for every probe() totally ignores possible dependencies. Regardless if using one thread per probe() call or if feeding probe() calls to just a few threads. Maybe that's why previous attempts to parallelize stuff failed. But that's just an assumption as I'm unaware of these previous attempts. Regards, Alexander Holler