Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932156AbbFDUjy (ORCPT ); Thu, 4 Jun 2015 16:39:54 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:55226 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752199AbbFDUjr (ORCPT ); Thu, 4 Jun 2015 16:39:47 -0400 Message-ID: <5570B783.1050808@ahsoftware.de> Date: Thu, 04 Jun 2015 22:39:31 +0200 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: "Grygorii.Strashko@linaro.org" , Tomeu Vizoso CC: Rob Herring , "linux-arm-kernel@lists.infradead.org" , =?UTF-8?B?U3TDqXBoYW5lIE1hcmNoZXNpbg==?= , Thierry Reding , Dmitry Torokhov , Grant Likely , Rob Herring , Mark Rutland , Dan Williams , "devicetree@vger.kernel.org" , dmaengine@vger.kernel.org, dri-devel , linux-clk@vger.kernel.org, "linux-fbdev@vger.kernel.org" , "linux-gpio@vger.kernel.org" , "linux-i2c@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , Linux PWM List , "linux-samsung-soc@vger.kernel.org" , "linux-tegra@vger.kernel.org" , Linux USB List Subject: Re: [PATCH 00/21] On-demand device registration References: <1432565608-26036-1-git-send-email-tomeu.vizoso@collabora.com> <556F5C24.1030101@linaro.org> In-Reply-To: <556F5C24.1030101@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2015 Lines: 45 Am 03.06.2015 um 21:57 schrieb Grygorii.Strashko@linaro.org: ... > So few comments from above: > - registering devices later during the System boot may improve boot time. > But resolving of all deferred probes may NOT improve boot time ;) > Have you seen smth like this? If someone is out for boot time reduction, I think one of the best ways would by making driver initialization parallel. Keep in mind that all linked in drivers currently are initialized in series. As it seems to have been forgotten or overread, I've mentioned in my series of patches last year that, with a few changes, it's possible to let the algorithm I've used (dfs) to spit out all drivers which can be initialized in parallel. But as I'm not paid for the work I've done and just did it out of curiosity, interest or how ever you want name it, I haven't spend any more time into that topic, especially as I'm missing the necessary connections to get patches into the kernel. ;) But, as said, it's easy (at least if aren't getting panic when it comes to a bit of algorithm theory) to get a list drivers you can start in parallel if you have such a complete list of dependencies as DT already offers. Just look at the pictures generate by dtc (using my patches), you will see, they already show which drivers can be initialized in parallel. So it would be easy to use e.g. all cores already very early at boot to initialize drivers, not just after init got started. Besides that the würgaround of defered init (which, btw. leads devs to supress error messages, which is especially bad if you are searching a problem) isn't needed anymore if you have a list of dependecies (however you get it, I've used DT because the dependencies already are all there). Regards, Alexander Holler -- 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/