Re: Announcement: Kernel with automatic boot tracing and prefetching available for testing (GSoC 2007)
Phillip Susi napisał(a): Krzysztof Lichota wrote: How it works? - During boot file accesses are recorded. - During subsequent boots this trace is used to prefetch files before they are used in order to speed up boot. How is the data prefetched? I know that the readahead package used the readahead() system call to load entire files that were accessed during boot. This is sub optimal because often times the entire file is not needed, only certain pages of it. Prefetch works on page-size chunks, so only used parts of files are prefetched. As for reading, prefetch uses force_page_cache_readahead(), so it is the same function as used by readahead() call. Also the readahead was done synchronously one file at a time, which does not keep the disk at full utilization. Ideally you just want to read in the required pages, in the order in which they are required, with several asynchronous requests in the queue at a time. This is good idea, it might improve results a bit. I will try it in the future. However, room for improvement is quite small, as you can see on this bootchart: http://prefetch.googlecode.com/svn/trunk/results/boot-prefetching/testmachine-kl1/test-9-versus-plain/bootchart-prefetch-sync.png During readahead disk is almost 100% utilized. You also want to wait until some of the data is read before continuing with the boot process, but you don't want to wait until ALL of it is read. It depends. I have done some experiments with asynchronous prefetching and in most cases it is better to wait for readahead to finish before proceeding than to let readahead go in parallel with execution of apps. This is consistent with results of other prefetching systems. The exception is when you can prefetch some files in advance, before execution of apps starts. This approach is used in prefetch to prefetch GUI in advance. The boot is split into 3 phases: 1. boot - since root partition is mounted until all filesystems are mounted 2. system - when all partitions are mounted till KDM/GDM is started 3. gui - when desktop environment is started Each phase is traced separately. For boot and system phase files are prefetched synchronously at start of the phase, but GUI phase files are prefetched in background right after system phase files are prefetched. I have done quite a lot of experiments to find the proper combination of parameters. See the page with descriptions of experiments: http://code.google.com/p/prefetch/wiki/InitialBootPrefetchingResults Of course there is always room for improvements. This implementation of prefetch is just the beginning :) Thanks for insightful comments. Krzysztof Lichota signature.asc Description: OpenPGP digital signature -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
new deskbar-applet update breaks tracker integration (Launchpad bug: 132455)
Greetings, So, this morning I woke up and ran my updates like everyday, and looked around at some changlogs/the gutsy changes rss feed,and noticed deskbar had been updated, with a new UI and everything. I won't go into the details here, but well, not everyone is pleased with the entirely new UI (with old in-panel and button-popup modes removed) If you want more on this, look here: https://bugs.launchpad.net/deskbar-applet/+bug/131446 and here: http://bugzilla.gnome.org/show_bug.cgi?id=465658). Anyways, along with this obvious change, I noticed my tracker search results were no longer showing up in the new deskbar. I check the preferences/installed extensions, and, although the libdeskbar-tracker package is still installed, deskbar no longer sees the tracker/tracker-live extensions. It looked like this is because the new deskbar requires extensions to be re-written. Obviously, since tracker is on the big new feature list, and is even listen on the tribe 4 announcment page (QUOTEYou can use Tracker in the search dialog, the file selector, nautilus, or the Deskbar applet/QUOTE), I see this as something fairly important. I'm more than willing to help as much as I can with this. And sorry if this should have been sent elsewhere/if someone else is already coving it. keep up the great work. Matt -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: OEM installer script, multi-use?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Phillip Lougher wrote: Anthony Yarusso wrote: I was wondering if someone who helped develop the OEM install option (or is familiar with it) knows whether it can be re-used. ie, if you're leasing machines, can you send it out to a client, get it back after a while and just run the script again to remove the old user and set it up for the next one to put in their preferences? Personally I would consider this too much of a security risk, personal or business sensitive data doesn't necessarily get removed once files are deleted. I would wipe or shred (both Linux commands) the disk before reuse. Phillip Would it be possible to get shred options included in the script for this sort of use? -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGwnzX6iO+5ByUi/QRAiMIAJ9qJrBHeujvIw8ZLs5z+TONRIMJRgCfQ/kg vIOLPbXRpAoF2/0HL4dRI2I= =pcYL -END PGP SIGNATURE- -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
Re: OEM installer script, multi-use?
Anthony Yarusso wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Phillip Lougher wrote: Anthony Yarusso wrote: I was wondering if someone who helped develop the OEM install option (or is familiar with it) knows whether it can be re-used. ie, if you're leasing machines, can you send it out to a client, get it back after a while and just run the script again to remove the old user and set it up for the next one to put in their preferences? Personally I would consider this too much of a security risk, personal or business sensitive data doesn't necessarily get removed once files are deleted. I would wipe or shred (both Linux commands) the disk before reuse. Phillip Would it be possible to get shred options included in the script for this sort of use? I think using wipe or shred on a drive would probably be a little over kill. dd zeros to the drive and then format would likely be enough to make the data prohibitively expensive to recover. This is of course depending on the data that was on the drive to begin with. For instance, I remember reading somewhere that the CIA destroys their hard drives in acid baths. The important part is to make recovery more expensive than the data is worth. As for the original question, I would say that it is going to be more trouble than its worth. I would much rather create a drive image with dd and then dd it back to the drive after every return. This would solve the above problem and you could likely create a network boot setup that did it automatically with a little work. Aka you would just plug the returning machine into a specialized network that would do all the needed stuff automatically. Btw, I'm not an ubuntu developer and I didn't help develop the oem installer, but I have had my head in the installer for other purposes. Someone may know a way of doing what you want, but I don't think it would be worth it either way. -- Ubuntu-devel-discuss mailing list Ubuntu-devel-discuss@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-devel-discuss
