From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Denk Date: Thu, 26 Feb 2009 22:33:26 +0100 Subject: [U-Boot] =?iso-8859-1?q?RE=A0=3A__Reduce_time_to_load?= In-Reply-To: <51D9710FF5643747BB605F97B8DE56CD0231C16E@STEGOSAURE.adetel.com> References: <51D9710FF5643747BB605F97B8DE56CD0231C16C@STEGOSAURE.adetel.com> <20090226113609.C64BC832E43F@gemini.denx.de> <51D9710FF5643747BB605F97B8DE56CD0231C16E@STEGOSAURE.adetel.com> Message-ID: <20090226213326.AFD8B832E43F@gemini.denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Dear Simon, In message <51D9710FF5643747BB605F97B8DE56CD0231C16E@STEGOSAURE.adetel.com> you wrote: > > U-boot take about 2 seconds to load the kernel. That sounds resonable, depending on the device you load Linux from. > The rest of the system take about 10 seconds until I get the prompt, so 10 seconds is a lot. I bet you use slow and/or big root file system, then. And how long does it take to start the real application, then? > it represents ~16% of total time needed to have an operational system. > I agree to say that most of the work to reduce boot time have to be done > on the kernel and userspace, but I'm trying to save as much time as > possible, even if it's 100ms. Well, trace the execution (for example by simply timestamping the messages printed by U-Boot - expect comes in handy to do that), and find out which poarts in U-Boot contribute most to these 2 seconds. The old rules that always apply are: you can trade off reliability for speed (like switching off image checksumming by setting the "verify" variable to "no"), and you can trade off cose (like flash memory foorprint) for speed (like using an uncompressed ext2 file system in a MTD device, preferrably on NOR flash). See the DULG for root file system selection, etc. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de A committee is a group that keeps the minutes and loses hours. -- Milton Berle