On Torsdag 30. april 2009, Vagrant Cascadian wrote: > do you still see a speed improvement using KDM vs. LDM with > LDM_DIRECTX=True ? this feature still uses ssh for the initial > connection (i.e. namely, the password negotiation),
I haven't heard about computer administrators testing that. What I've heard is an other story that you already know. Many schools are running LTSP thin clients on really old or cheap computers with scare resources. We saw this in Norwegian schools three years ago, when upgrading to Skolelinux 3.0 with LDM. Half of the clients stopped working, or become to slow. The reason was twofold. Many clients got only 32 MB RAM. LDM used around 50 MB RAM to run. The clients got a black screen when booting, even if the LTSP started nicely in the first place. Also, clients with 64 MB RAM did not run smoothly when having a ssh tunnel running, cause the added computational power needed to decrypt the traffic. Then computer administrators downgrade to a prior version of LTSP without LDM. Or else 250 machines that worked easily with Skolelinux 2.0, just stopped working when upgrading. Luckily the schools in this example got additional grant last year to buy new machines. Now they run Low Fat clients (diskless) on most machines. Their bottleneck experiences then vaporised. That said, it's a greater perspective here. Some computer administrators has told us that the security level provided with a switched network is more than enough for them. Since we are providing netgroups bound to a MAC address, you can't get root access to the network with a random connected laptop. It's a bigger problem that kids have written their password on a note in their pencil case. A Note that can easily be red by a fellow student. An other school system admin told me: If a 14 year kid is able to do package sniffing on a switched network, we should consider commending them instead of sending a not home to their parents on how to behave. My take on this, is that's much more to be gained speeding up other parts of the boot sequence. LDM or KDM is not the real time thief's if you're looking ahead. It's often before that in the boot process, starting services not needed, the file system (as shown with speed improvements between ext3 and ext4) etc. It's put into play a whole lot of resources now from Ubuntu, Mandrive, Nokia, Intel, KDE, Gnome etc. to make Linux boot really fast, having full power management capabilities (sawing power), with a full fledged desktop system. Initiatives as Maemo, Moblin and KDE Plasma points in that direction. This improvements has already been committed upstream to different projects, and will finds it's ways into Debian sooner than later. We are soon in a luxury situation, to make the right blend of options. Earlier we had to do a lot of plumbing to make things integrate nicely. Of course plumbing are still necessary. But we also got much more solutions ready than before. Now we can make a laptop, netbook or mobile Internet device work together with a Skolelinux or a K12LTSP network pretty easy. It's often about taking small chunks of code already made, and integrate that to the standard network solutions provided with school distroes. I'm helping out with such initiatives just as we speak. A student project are working with the network manager code shipped with many Linux distributions. This work is committed to Debian through alioth, but also upstream to the network manager repository. Best regards Knut Yrvin -- Skolelinux, relation manager cell: + 47 934 79 561, phone: +47 21 60 27 58 http://www.skolelinux.no -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected]
