From mboxrd@z Thu Jan 1 00:00:00 1970 From: Diego Calleja Date: Mon, 14 Feb 2005 23:43:29 +0000 Subject: Re: [ANNOUNCE] hotplug-ng 001 release Message-Id: <20050215004329.5b96b5a1.diegocg@gmail.com> List-Id: References: <20050211004033.GA26624@suse.de> <420C054B.1070502@downeast.net> <20050211011609.GA27176@suse.de> <1108354011.25912.43.camel@krustophenia.net> <4d8e3fd305021400323fa01fff@mail.gmail.com> <42106685.40307@arcor.de> <1108422240.28902.11.camel@krustophenia.net> In-Reply-To: <1108422240.28902.11.camel@krustophenia.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: Lee Revell Cc: prakashp@arcor.de, paolo.ciarrocchi@gmail.com, gregkh@suse.de, pmcfarland@downeast.net, linux-hotplug-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org El Mon, 14 Feb 2005 18:04:00 -0500, Lee Revell escribi=F3: > Last I heard Gentoo does not even do it by default. >=20 > I don't see why so much effort goes into improving boot time on the > kernel side when the most obvious user space problem is ignored. There's stuff that it could be done in the kernel to help improving those n= umbers, IMHO. xp logs all the io done the first two minutes after booting. The next time = it boots it tries to read all those files at once so the programs will find stuff in= memory instead of having to do lots of small seeks. Some people in the linux field= have got a list of the files used at startup and they've thrown it at a "readhea= d" script, which seems to help but IMHO it's somewhat "hacky" compared with the=20 xp's trick. xp also does that when you start a program, it saves a log of a= ll the io done and it preloads it efficiently at startup - it improves "cold-cache= " loading times a _lot_. I haven't seen any alternative for that in the linux world, = and being able to keep track of al the io done by a given process would fix tha= t (some people has put used printk's for that, but i think it can be done better) Also, it analyzes all those io "logs" and defragments (in background every = 3 days, and with low load without the user noticing it) the disk according to the _= use_ of the systems. Linux kernel can keep a file unfragmented, but currently there's n= o way linux can do decisions like "this system starts openoffice, so I'm going to= move the binaries to another place of the disk where they'll load faster" or "when X= program uses /lib/libfoo.so it also uses /lib/libbar.so, so I'm going to put those = two together in the disk because that will avoid seeks". Kernel only can keep a single f= ile unfragmented, but it doesn't know about how several files must be (un)fragm= ented between them. Being able to defragment things seems to be the one fix that = (even mac os x does it) Userspace is where the problem is, but it's not going to be fixed. Ever. If something, it's going to be worse - it's how software works. And even if yo= u make openoffice "fast", you still could _improve_ things with the tricks describ= ed above. Disks are too slow, and things like demand-loading executables gener= ate too many small seeks, and programs can't control demand-loading so I don't think userspace is the only with work to do. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id=14396&op=CCk _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel