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Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Lennart Poettering writes about the Fedora 17 multiseat feature. "With this code in Fedora 17 we cover the big use cases of multi-seat already: internet cafes, class rooms and similar installations can provide PC workplaces cheaply and easily without any manual configuration. Later on we want to build on this and make this useful for different uses too: for example, the ability to get a login screen as easily as plugging in a USB connector makes this not useful only for saving money in setups for many people, but also in embedded environments (consider monitoring/debugging screens made available via this hotplug logic) or servers (get trivially quick local access to your otherwise head-less server)."
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Raw video demonstration (for users without Flash)

Posted May 2, 2012 14:24 UTC (Wed) by aorth (guest, #55260) [Link]

He links to a video, but it's using an SWF player. If you don't have flash installed, you can find the raw video here:

http://s3.amazonaws.com/ksr/projects/153458/video-102678-...

Looks pretty cool.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 16:18 UTC (Wed) by epa (subscriber, #39769) [Link]

Seriously useful stuff for environments with large numbers of users, like university computer labs (if those still exist). It does require the control groups stuff to be pretty bulletproof to make sure that one user can't unduly slow down or crash another user's session. I expect that in future versions of Fedora we will see more work towards making the system multiuser-safe by default.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 16:36 UTC (Wed) by drag (subscriber, #31333) [Link]

> I expect that in future versions of Fedora we will see more work towards making the system multiuser-safe by default.

Maybe. I suppose it depends on how popular it gets.

What is going to be interesting is that while it probably works now, will it still work well when Fedora 20 comes out?

We have seen multiseat efforts in the past, but they never quite come to fruition and bit-rot on vine. So they lose what usefulness they may have had at some point. If the new 'tight integration' approach using things systemd/udev/consolekit/cgroups/etc works out well enough that it stays useful for a long them then that will go a long way to prove that this design approach is the correct one.

If they are not able to maintain it and it breaks after a couple Fedora releases then it's not going to be much better then we had before were things worked well if you could manage to figure out how to configure things correct and it requires significant effort to keep customized setups working well between major version.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 0:14 UTC (Thu) by daniels (subscriber, #16193) [Link]

We have seen multiseat efforts in the past, but they never quite come to fruition and bit-rot on vine.

Speaking as the author of one of them (Ubuntu's multiseat package), the primary reason is that they were pretty much all spectacular hacks. Some less so than others (Ubuntu's was the cleanest of them all at the time - most others required a very unpleasantly patched server whereas we did it out of the box), but most of them were very difficult to support in the long term, especially since we were fighting against the underlying system rather than working with it.

The other, perhaps less important, reason is that pretty much all the efforts I know of were either done for specific projects (like the Brazilian one) with perhaps a limited lifespan, or were commercial imperatives to support certain product lines, again with a limited lifespan.

I'm a lot more optimistic about the systemd stuff than I was about any of the others.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 23:10 UTC (Wed) by gdt (subscriber, #6284) [Link]

like university computer labs...

Uni computing labs are a size up from where this is useful, they have 40 to 400 computers whereas multi-head is more useful for 4.

The length limitations of USB cabling means you can't cheaply move expensive and privacy-sensitive hardware out of the computing lab and into a secure space. The cheapest ethernet-using robust computers are small form factor PCs, with a trend to have no unreliable rotating storage but using cheap CF cards. They are usually configured as stateless or puppet-maintained computers.

Once they get graphics card sharing going then you might want to connect multiple screens and keyboards to those lab computers.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 0:24 UTC (Thu) by josh (subscriber, #17465) [Link]

> Uni computing labs are a size up from where this is useful, they have 40 to 400 computers whereas multi-head is more useful for 4.

You can still use multi-head to have four monitors/keyboards/mice per physical box, reducing your lab from 40-400 systems to 10-100 systems.

Also, USB-over-Ethernet extenders exist, and you could use those to run a whole lab from a small handful of servers. Many computer labs already use semi-thin clients (where you SSH elsewhere if you want a pile of computing power), and this seems like a natural extension.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 13:28 UTC (Thu) by drag (subscriber, #31333) [Link]

Not to also mention that off the shelf consumer hardware is significantly cheaper and more powerful then what you typically see with thin client hardware. So even if you are just provisioning for thin clients or 'semi-thin clients' you can still come out ahead.

However, The type of VGA/keyboard/mouse clients were you have a small box you connect to a desktop/desktop server type thing over long twisted wire pairs do have a significant advantage that they are mostly tamper proof and are useless to the thief if stolen.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 16:42 UTC (Wed) by jra (subscriber, #55261) [Link]

I really like Lennart's work, and this looks like a wonderful project, but does he *really* have to try and slam Ubuntu every chance he gets. (I'm talking about this section:

"Oh, and BTW, as Ubuntu appears to be "focussing" on "clarity" in the "cloud" now ;-), and chose Upstart instead of systemd, this feature won't be available in Ubuntu any time soon. That's (one detail of) the price Ubuntu has to pay for choosing to maintain it's own (largely legacy, such as ConsoleKit) plumbing stack."

That section could have been removed from the article without detracting at all from the information in it. In order for Fedora to "win", Ubuntu does not have to lose.

It's such a shame and it detracts from the technical excellence of what he otherwise does.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 16:59 UTC (Wed) by rvfh (subscriber, #31018) [Link]

Seems we are basically saying the same thing. Happy to see I am not the only one!

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 19:43 UTC (Wed) by tuna (guest, #44480) [Link]

"That section could have been removed from the article without detracting at all from the information in it. In order for Fedora to "win", Ubuntu does not have to lose."

This LWN article links to Poettering's blog post, not a news article. If you have to be diplomatic to Ubuntu/Fedora/other fanboys (or fangirls) all the time, what is the fun of having a blog?

IMO, you are allowed to gloat if you do something good.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 21:26 UTC (Wed) by engla (guest, #47454) [Link]

> IMO, you are allowed to gloat if you do something good.

It's divisive. Some will cheer you on and for others you will look dumb. I'd prefer Lennart didn't make Ubuntu's choice into a We vs. Them scenario.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 22:53 UTC (Wed) by drag (subscriber, #31333) [Link]

I don't think it's a big sin.

Especially when Mark Shuttleworth writes a blog post about your product claiming that he can't use it because it has substandard quality due to inherent bad design choices and has no testing behind it.

I know I would find that irritating and would want to point out when my project does something really cool in a relatively simple manner due to it's design.

That being said it's not classy. Just goes to show the guy can be easily provoked. Not a big deal, IMO.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 1:33 UTC (Thu) by jmorris42 (guest, #2203) [Link]

> I don't think it's a big sin.

Agreed. This is a pretty big win if it really works in the real world. I'd say big enough to finally justify all the bluster about systemd in the first place. To date it has been more pain than gain for most users, this development promises to change that equation entirely by having a major feature to point to.

So let him gloat a bit, especially since Ubuntu started this particular blogwar.

Not saying I'm going to stop saying nasty things about Poettering from time to time when he strays from the "Unix Way". Most of the time he seems to either be really wrong or really right. This time he is looking really right. MultiSeat is about as "Unix Way" as it gets.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 2:52 UTC (Thu) by jonabbey (guest, #2736) [Link]

systems (and pam_systemd in particular) are already a big deal. It's helping us out a lot in letting us safely efficiently use some big Fedora 16 systems as remote browsing servers with NX.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 2:53 UTC (Thu) by jonabbey (guest, #2736) [Link]

systemd, not systems, gah.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 10:05 UTC (Thu) by ovitters (subscriber, #27950) [Link]

He likes to advocate what he believes is right. He does so in real life and similar in his blog.

Though he does a lot of advocacy, you can criticise him all you want. Just be prepared for a (eventual) long technical argument. Eventually he might or might not agree with you... but it seems to be always based on what is technically the best solution.

I'm not sure the advocacy is effective in getting his points across for all cultures. E.g. seems to be interpreted as personal by some. I like the clarity it gives.

Not saying something because it might be considered politically correct by some: clearly he does things different.

Ubuntu bashing

Posted May 2, 2012 16:57 UTC (Wed) by rvfh (subscriber, #31018) [Link]

Weird how he needs to bash Ubuntu in the middle of the article for not having systemd and thus missing this feature, ignoring the fact that Ubuntu has had easy to install LTSP support for quite some time, and which AFAICS Fedora lacks (the helpers, not LTSP itself, of course).

Not trying to troll here, but I personally would love to have both in one distribution, with Gnome _and_ KDE support, and which you can name whatever you want (Feduntu comes to mind.) All this incessant bashing is really useless, and distracts form the beauty of the feature presented, which BTW I find stunning.

Ubuntu bashing

Posted May 2, 2012 17:11 UTC (Wed) by dlang (subscriber, #313) [Link]

Doesn't Ubuntu allow you to have both Gnome and KDE? (as well as several other options)

the default DE for Ubuntu is Unity, but you can install gnome and kde trivially (apt-get install kubuntu-desktop gnome-desktop or the gui equivalent)

given the size of the various DEs and their dependancies, it makes sense to not try and cram both on a single CD install media.

Ubuntu bashing

Posted May 2, 2012 17:44 UTC (Wed) by drag (subscriber, #31333) [Link]

I can install KDE and many other DEs on Fedora also.

The problem is that people always argue that desktop environments gets shortchanged by distributions unless it's available at install time.

I have never seen it that way, but whatever.

Ubuntu bashing

Posted May 2, 2012 17:49 UTC (Wed) by dlang (subscriber, #313) [Link]

> The problem is that people always argue that desktop environments gets shortchanged by distributions unless it's available at install time.

Ubuntu has spins for most of the DEs where the spin propritizes that DE (kubuntu for KDE, lubuntu for LXDE, etc), so I'd say it's a little less true than for distros that don't offer such spins.

Ubuntu bashing

Posted May 2, 2012 18:12 UTC (Wed) by drag (subscriber, #31333) [Link]

>Ubuntu has spins for most of the DEs where the spin propritizes that DE (kubuntu for KDE, lubuntu for LXDE, etc),

like these ?
http://spins.fedoraproject.org/

> so I'd say it's a little less true than for distros that don't offer such spins.

Personally I think it's silly. I never understood what was so horrible about 'tasksel install kde-desktop' or whatever is the equivalent.

Ubuntu bashing

Posted May 2, 2012 21:00 UTC (Wed) by rvfh (subscriber, #31018) [Link]

> Doesn't Ubuntu allow you to have both Gnome and KDE? (as well as several other options)

Yes indeed, my point was triggered by the fact that the support in Fedora for the feature the blog is about is (for now) only available for Gnome.

Don't get me wrong: I am not saying that Mr Poettering should implement it for all DEs, of course. If the KDE devs find the functionality attractive I am sure they can implement it.

The whole point is that I'm tired of this bashing of one side to other, especially Fedora vs Ubuntu: Unity vs Gnome, RPM vs Deb, yum vs apt, one multiarch vs the other multiarch. What a PITA! Guys, do you know that Samsung, the champion of Android on high-end phones plans to have the Galaxy S3 run Windows 8 by October? Let's stop fighting between ourselves: the real competitor is out there!!!

Ubuntu bashing

Posted May 3, 2012 17:20 UTC (Thu) by jspaleta (subscriber, #50639) [Link]

He in fact points to a freedesktop url so that display manager writers can learn how to hook into the systemd specific bits correctly to get access to this.

He's not thumbing his nose at anyone. He's not gloating. He's going... this is cool... and we have it working in GNOME's GDM in Fedora 17... we'd love for other display managers and other distributions to get this working too. We've even provided some high level instructional material for developers of other display managers to help them figure out what they need to do to hook in.

Look here
http://www.freedesktop.org/wiki/Software/systemd/writing-...
and here
http://www.freedesktop.org/wiki/Software/systemd/multiseat

Oh and if you need hardware to test...they can send up some demo units of the pluggable hardware to test. I mean holy crap... offers of free hardware to test against. He's bending over backwards to make it as easy as possible for other implementations to getting support for this coded in.

If the kdm developers want this feature...its not going to be a big deal for them to add. If the developers of lightdm wants this feature...they can probably get it as well. However, I don't expect lightdm developers to make it a priority, as its very Unity specific and if Ubuntu doesn't make the jump to systemd there will be very little pressure to get lightdm extended to support a systemd specific capability. But stranger things have happened.

If Canonical wants to really go after the enterprise desktop space, this would seem like an important feature. Being able to really position Ubuntu better in the thin client market... and maybe even the point of sale markets. This functionality is a business win. The fact that Canonical doesn't see that is troubling. Especially if this works out of the box with livecds...and you can demo the functionality from a cold boot using some random laptop at a meeting with a customer with no icky low level configuration. Enterprise oriented sales teams must be drooling over this.

And FYI, the key here is GDM... not strictly limited to "GNOME the desktop". I'm pretty sure xfce as a session under GDM in Fedora 17 works just fine. Unity2d would probably work fine as well..if there was a systemd using distribution shipping a Unity2d session definition for gdm to expose.

-jef

LTSP vs multi-seat

Posted May 2, 2012 17:18 UTC (Wed) by jreiser (subscriber, #11027) [Link]

About the only commonality between LTSP and multi-seat is the number of displays, keyboards, and mice. Multi-seat has 1 "computer [box]", one hardware display card [although can be more], one filesystem. LTSP has one "computer [box]" per seat, one hardware display card per seat, often one root filesystem per seat. LTSP uses ethernet, multi-seat uses USB2.0 [often in "star" configuration, although using hubs and/or daisy-chaining also works.]

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 17:09 UTC (Wed) by geuder (subscriber, #62854) [Link]

Yes, there should be a market for this. A somewhat different approach to the same problem has existed for a couple of years http://www.ltsp.org/ . I have once installed it on Ubuntu 10.04 and it went quite smoothly. It's in use in some schools in this country (typically they use last generation PCs as terminals).

The promised $50 price point per seat neglects the display and the keyboard. The Amazon offer linked from the article incl. display and keyboard is already at $290. So the difference to a small netbook is not that big anymore, although administration is easier and ergonomics for the user is better.

Unfortunately in schools there is heavy competition by M$ offering their stuff for dumping prices for obvious reasons.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 7, 2012 15:19 UTC (Mon) by Lennie (guest, #49641) [Link]

I was kind of surprised by the 50 dollar price point if it is just an USB-device, a Raspberry Pi which does include a CPU is cheaper and has no problems with distance (the USB-connection doesn't need to be extended, as the Raspberry Pi already has Ethernet).

Fedora here I come!

Posted May 2, 2012 17:10 UTC (Wed) by Felix_the_Mac (guest, #32242) [Link]

I think I will jump to Fedora (from Ubuntu) and set this up so the kids and I can compute at the same time rather than take turns.

I wonder if you can play multiplayer games against each other? (I don't have any in mind, our current favourite is njam (pacman clone).

I will probably wait until Pluggable release a USB3, 1920x1080 docking station.

Fedora here I come!

Posted May 2, 2012 19:01 UTC (Wed) by kragil (guest, #34373) [Link]

Beware, Fedora is always fairly broken at first. An Ubuntu LTS and a Fedora release are worlds apart when it comes to general usability/stability.
I run both (stable and betas) and Fedora has way more bugs and regressions (right now, suspend is broken again in F17 and scala does not work because F17 ships with JDK 1.7 and the scala version somehow exspects 1.6. Obvious stuff like that are not likely to happen in Ubuntu because most of the software first goes through Debians rigorous testing.)

So expect to pay a fairly high price for this feature, but if you really need it go ahead.

Fedora here I come!

Posted May 2, 2012 19:04 UTC (Wed) by drag (subscriber, #31333) [Link]

That's the general rule with Fedora.

Anybody installing it who don't want to fool around that much should
A) Wait a month or so
B) Be prepared to download about 300-400 MB of updates.

Fedora here I come!

Posted May 2, 2012 21:56 UTC (Wed) by dowdle (subscriber, #659) [Link]

Just out of curiosity, how would you compare the Ubuntu LTS releases against each non-LTS releases with regards to stability?

I use Fedora in computer labs and on my personal desktops and I rarely run into problems... although a lot would depend on how many packages one has installed and commonly use... and the hardware you are running it on. I use fairly common, business class Dell desktops and laptops and almost never have hardware issues... so your mileage may vary. I've seen hardware that hates one distro and loves another and vice versa. Fedora generally just works for me.

From what I've read, Ubuntu provides about 12-16% of their own packages that are not vetted in Debian's repos.

I don't think this is worth arguing over but I think your comparison of the stability of Ubuntu vs Fedora was overstated... at least it was from my perspective. Obviously not from yours though, eh?

Fedora here I come!

Posted May 3, 2012 7:08 UTC (Thu) by geuder (subscriber, #62854) [Link]

> Just out of curiosity, how would you compare the Ubuntu LTS releases
> against each non-LTS releases with regards to stability?

I don't think I have seen any pattern. If things are broken they are broken, bugs don't look at the release classification. (I don't know whether Ubuntu project has stricter release quality criteria for LTS, but I think the biggest limiting factor is testing and bug-fixing resources. And they don't magically grow when its LTS time every second year.)

Maybe the chance of getting a fix in the same release is slightly better if it is LTS. For non-LTS you wait half a year and there is the next release. Just a feeling, though. I have no statistics and generally the number of serious breakages is too small and/or affects only some particular hardware, so statistics might not be very useful.

Fedora here I come!

Posted May 3, 2012 7:19 UTC (Thu) by kragil (guest, #34373) [Link]

Well, a LTS release is the end of a meta-cycle where Canonicals own software is supposed to be mature and stable. With regard to Unity it shows. In 11.04 and 11.10 it was barely usable and now it works fairly OK.
AFAIK a LTS is based on Debian Testing instead of Unstable, so even more fixes there. The development is also more conservative and more focused on polishing and fixing than on new features.
It all adds up and as a general rule a LTS is definitely better than a non-LTS.

Fedora here I come!

Posted May 3, 2012 7:28 UTC (Thu) by geuder (subscriber, #62854) [Link]

>Well, a LTS release is the end of a meta-cycle where Canonicals own
> software is supposed to be mature and stable. With regard to Unity it shows.

True for Unity. However, I don't remember any comparable case from Hardy or Lucid, so I think it's a bit early to generalize. Not sure whether they really planned such a long and rocky road for Unity when they started the project, it might well be just by accident that it happened to be "ready" for LTS.

Fedora here I come!

Posted May 3, 2012 17:37 UTC (Thu) by jspaleta (subscriber, #50639) [Link]

I'm pretty sure they implemented more aggressive QA processes ahead of the LTS this time. If you look at the chatter and the talking points among the engineering teams, QA process definitely seems to have been in sharper focus for this time. So I don't think its so much a matter of accident as it is a direct result of cycling back and re-examining the pre-release QA process and making some adjustments so more testing is actually getting done.

For as much flack as I give Canonical for having no idea how to cultivate a sustainable business model... the engineering side seems to getting better and technical project management with the resource they are alotted. There are without a doubt some very good lessons learned about how to implement agile development (and cycle back to re-optimize out bottlenecks) inside the Canonical engineering fenceline. Hopefully they spend some time talking about the recent QA process rework at some conferences in front of other project developers and try to throw some process nuggets out for people to take back and integrate into their workflows.

-jef

Fedora here I come!

Posted May 21, 2012 9:13 UTC (Mon) by kragil (guest, #34373) [Link]

Repeat after me:
Canonical needs to "cultivate a sustainable business model" like Chelsea needs to do the same.
That is NEVER. As long as capitalism survives Canonical will survive, because Mark has more money than he can ever spend on Canonical/Ubuntu. He spends more on NY penthouses than he does on Ubuntu. He is not going to have kids (he does not want to and isn't able to anymore).
So Canonical is going to be around forever and will always be able to burn 10s or 100s of millions. No problem. Arguing about how long Mark will keep this up is pretty pointless, when it costs him next to nothing to sustain Canonical. Your common car tuner spends way more of his income on his hobby than Mark.
And just like Chelsea with luck you can win the Champions League with that strategy. There is no reason why Ubuntu can't do the same.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 17:19 UTC (Wed) by geuder (subscriber, #62854) [Link]

BTW what's the maximum USB cable length these days? I remember some 5 years ago my then employer's product failed to pass USB certification because of a cable length problem. And then we were talking only about 1.5 meters.

LTSP uses Ethernet, so there should be no cabling issues.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 17:58 UTC (Wed) by gevaerts (subscriber, #21521) [Link]

5 meters, same as it's always been.

Note that that's the length of a single USB cable. If you add repeaters (such as USB hubs, or possibly extenders that use fibre or other systems), you can easily get beyond that.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 18:52 UTC (Wed) by geuder (subscriber, #62854) [Link]

OK. Maybe we didn't pass the certification because the spec required 5 meters and we had done all testing using 1.5 m. I don't recall the details and I'm not a HW guy anyway.

Yes, I'm aware that there are fiber extensions, but I without knowing the details this does not sound attractive to me if one of the major goals is cost.

If you think about class room cabling you often have to go up to the ceiling and down to the next desk row again. There went your 5 meters... So even using hubs this sounds challenging to me.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 2, 2012 19:06 UTC (Wed) by dlang (subscriber, #313) [Link]

> If you think about class room cabling you often have to go up to the ceiling and down to the next desk row again. There went your 5 meters... So even using hubs this sounds challenging to me.

no, you put one computer at each group of desks with one computer in the middle and 4+ people sitting around it.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 7:19 UTC (Thu) by geuder (subscriber, #62854) [Link]

> no, you put one computer at each group of desks with one computer in the
> middle and 4+ people sitting around it.

From an administrators point of view I'd prefer to have one server for the whole classroom (Yeah, it's also a single point of failure, but I don't think that's a major issue.)

Disclaimer: I haven't been involved in buying such hardware for a long time, so I'm not sure whether 4-5 small servers are less expensive than 1 equivalent one.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 8:38 UTC (Thu) by dlang (subscriber, #313) [Link]

how much memory are you expecting to give each person?

nowdays 2G per person doesn't cut it, 4G can be tight.

While you can stuff huge amounts of ram in a super powerful server, you end up paying a very significant price premium for the density. you can generally get 2-3x the total ram and clock cycles if you drop from the very top end down to the commodity level.

Not to mention that with several smaller systems you can then use cheap display/keyboard connections (that are limited to short distances) as opposed to paying the much higher costs for ones that go longer distances.

besides, if you have one server for the whole classroom, when that server has problems, everything stops. If you have a dozen machines instead and one fails, it has far less impact (and you may even be able to afford a spare :-)

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 9:20 UTC (Thu) by BlueLightning (subscriber, #38978) [Link]

> nowdays 2G per person doesn't cut it, 4G can be tight.

Surely that depends entirely on what you're doing with the machine. As I sit here I'm only using 1.1GB of the 4GB my machine has and that's a KDE desktop with a browser (11 tabs open), email client, text editor and console with multiple tabs running as well as a bunch of daemons in the background. Not to mention that in a multi-seat situation some of that would be common and some of it would be able to be shared between users as well.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 10:46 UTC (Thu) by geuder (subscriber, #62854) [Link]

> nowdays 2G per person doesn't cut it, 4G can be tight.

What are you doing?

I type this comment on a 512 MB machine. It runs a full Kubuntu (KDE not being known to be the most lightweight) and normal web browsing and text editing just work fine. LibreOffice brings the machine to swap a bit too much admittedly. Not that I would really be forced to use it, but IBM T40 is just a nice museum hardware and the small memory does not really disturb me.

On my work machines I have 4 GB and I hardly remember them swapping. Well, if I run 3 or more virtual machines I can feel memory getting short.

So for most classrooms 768 MB - 1 GB per user should be more than enough. Unless they compile Qt or do 3D modeling of course...

> If you have a dozen machines instead and one fails, it has far less impact

True for you and me, because we could start hacking around. However, not an option in many schools. There you pay extra for each administration job.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 6, 2012 14:33 UTC (Sun) by salimma (subscriber, #34460) [Link]

Remember that the users are actually running on a single OS instance. So shared libraries etc. are amortized across all users -- and I'm betting that, in a lab setting, the sysadmins would restrict users to running a single desktop if memory constraints really become problematic.

Now, if they all open 30+ tabs in Firefox... *shudder*

Please clarify how Multi-seat works...???

Posted May 2, 2012 18:30 UTC (Wed) by pr1268 (subscriber, #24648) [Link]

Allow me to understand correctly: Is that multi-seat "Pluggable Universal Laptop Docking Station" (on the Amazon.com link above) just like a KVM switch with network (RJ-45 jack, I presume), and sound (3.5mm stereo mini-plugs for both output sound and input/microphone)? And it all works via USB 2.0?

If so, then fascinating! (I should crawl out from under the rock I'm living every so often. ;-) )

P.S. I'm assuming it's not limited to just a laptop; i.e. desktop workstations could also make use of this, as Lennart's article suggests.

Please clarify how Multi-seat works...???

Posted May 2, 2012 19:19 UTC (Wed) by drag (subscriber, #31333) [Link]

Internally it will be basically two hubs

USB 2.0 port from PC ---> HUB1 --> Displaylink USB + USB Ethernet + USB Audio + USB HUB2 ---> 4 USB ports.

Yeah it's pretty awesome considering how little bandwidth you have to work with. USB 2.0 is about 60MB/s rate with the ability to push about 30-40MB/s if your lucky. Seems like USB harddrives stick around 20-25MB/s

When USB 3.0 and/or thunderbolt devices start coming out it's going to be even cooler. :) USB 3.0 should get you around 300-450MB/s of real-world bandwidth.

Thunderbolt seems like it has the potential to be a universal interface. So you would end up with a single chip on your computer that would provide all your basic I/O functions of network/SATA/digital display/USB 3.0/PCI-E all multiplexed over one type of external port and one type of cable. (thunderbolt devices demultiplex internally)

Please clarify how Multi-seat works...???

Posted May 2, 2012 21:25 UTC (Wed) by raven667 (subscriber, #5198) [Link]

> Thunderbolt seems like it has the potential to be a universal interface.

For some reason probably related to network effects of existing deployed systems this never seems to work out in practice. Before Thunderbolt there was Firewire and before that SCSI and the granddaddy of them all Ethernet but none became a universal connector standard. The most successful has been USB, which was only built as a reaction to non-technical issues with Firewire.

USB has very successfully targeted low bandwidth devices. even USB2 isn't even as fast as the original Firewire 400 from the 1990s . I don't see Thunderbolt or another connector replacing it anytime soon, there are still going to be a smattering of different connectors such as Thunderbolt, eSATA, USB and Ethernet for the foreseeable future.

Please clarify how Multi-seat works...???

Posted May 2, 2012 21:43 UTC (Wed) by engla (guest, #47454) [Link]

Thunderbolt is both a display cable and a data cable, which is more than USB or Ethernet.

Please clarify how Multi-seat works...???

Posted May 2, 2012 23:25 UTC (Wed) by drag (subscriber, #31333) [Link]

[quote]
USB has very successfully targeted low bandwidth devices. even USB2 isn't even as fast as the original Firewire 400 from the 1990s . I don't see Thunderbolt or another connector replacing it anytime soon, there are still going to be a smattering of different connectors such as Thunderbolt, eSATA, USB and Ethernet for the foreseeable future.[/quote]

That is why you'd do things like have a USB 3.0 controller or eSATA controllers that plug into your thunderbolt port. :) It's not going to replace any of that. It's just going to allow you to plug in fiendishly large amounts of devices into you computer.

With 2 thunderbolt ports you could do things like connect up to 12 ethernet cards. If you have ones that have two ethernet ports then that is 24 ports, which would make for a cheap 24 port Linux router for a 1Gp/s network.

Also you can use it in conjunction with IOMMU and hand over PCIe devices you plug into the thunderbolt port to your KVM virtual machines.

What it really boils down to is cost. If the demodulate chip for thunderbolt and wiring costs too much then nobody will use it.

Thunderbolt

Posted May 8, 2012 8:36 UTC (Tue) by job (guest, #670) [Link]

You can already see this with Apple computers. They didn't offer docking stations for their laptops, which I thought was a shame, but now they do offer Thunderbolt connectors instead. The monitor becomes the docking station where keyboard and ethernet is constantly connected. You can even keep it when you change laptop models! Connecting more than one head per computer could hopefully be a natural extension of this.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 10:49 UTC (Thu) by bangert (subscriber, #28342) [Link]

incidentally, by now this must be the most-advertised fedora 17 feature...

i didnt realize before now, but Lennart Poettering is becoming a rock star.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 7, 2012 19:58 UTC (Mon) by linusw (subscriber, #40300) [Link]

This has been a desired feature in Fedora since 2009, when it was driven by Chris Tyler. All Poettering did was to step in, pick the item from the feature list, and do the actual work required. (Well that was not that little, actually.) Here is the stale feature page from way back:
http://fedoraproject.org/wiki/Features/Multiseat

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 3, 2012 21:14 UTC (Thu) by cdmiller (subscriber, #2813) [Link]

It's unclear from the article and video whether this is an improvement over existing multi seat X implementations. Does anyone have a feel for how it compares? In the past with the right hardware the software setup for the ubuntu multiseatX was fairly simple.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 8, 2012 8:38 UTC (Tue) by job (guest, #670) [Link]

It will be easier to maintain (all multiseat installations in Linux are more or less hacks), and hopefully easier to use (just plug it in).

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 7, 2012 3:51 UTC (Mon) by Baylink (guest, #755) [Link]

Wow...

it sure is good to hear that Fedora has figured out how to have multiple users on a Unix box.

(1993, PCs Limited 386/16, 6MB RAM, 19 users)

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 7, 2012 5:00 UTC (Mon) by rahulsundaram (subscriber, #21946) [Link]

Assuming you are merely ignorant and haven't read the blog post at all, multi-seat != multi-user

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 8, 2012 1:07 UTC (Tue) by malor (guest, #2973) [Link]

Well, Poettering is still reinventing old, old technology. Multi-head Unix boxes have been around for decades.

The big problem was that even serial terminals were ridiculously overpriced, more expensive than just buying a cheap PC and running a terminal emulator. And actual X terminals were insanely expensive.

You can sort of argue that these weren't 'multihead', because the video signal was generated by the terminal, but I don't think that's a good way to define it. All the processing still happened on the host. Serial terminals were mostly pretty stupid, with the exception of some, um, I think it was Tektronix models that had bit-addressable graphics. There was a fair bit more to an X terminal, as it was actually running the X server locally, but it was still really 'multihead' in most senses. The terminal wouldn't do anything by itself, it was just a smart display device for its attached machine.

It looks like Poettering's solution isn't really 'true' multihead either. It's still the same basic idea, but running over USB instead. And I gather it doesn't yet support regular text gettys, so it's not even a full replacement for oldschool serial terminals.

It wouldn't even be necessary, except for the loss of network transparency in GNOME and KDE. All you'd need, if the desktops still worked properly over a network, would be a Raspberry Pi at each terminal to run the screen and keyboard, and you'd be 'multihead' as much as any Unix machine ever was, back in the old days, and certainly as much as running this solution.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 8, 2012 1:17 UTC (Tue) by Cyberax (✭ supporter ✭, #52523) [Link]

Lennart's solution can be easily reworked to work with several X servers (even remote ones). It's the beauty of systemd - it's a generic session manager that can be used for just about anything.

Actually, it already should work with xdcmp and gdm. But I haven't checked this personally.

And no, true multihead hasn't been done properly up until now.

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted May 7, 2012 7:33 UTC (Mon) by anselm (subscriber, #2796) [Link]

(1993, PCs Limited 386/16, 6MB RAM, 19 users)

Great. I bet they were all running X!?

Poettering: The Most Awesome, Least-Advertised Fedora 17 Feature

Posted Jun 15, 2012 3:11 UTC (Fri) by Baylink (guest, #755) [Link]

Sure; 19 X servers in 6MB of RAM. :-)

Note, though, that if -- as some people suggested -- I had been running X terminals, it would indeed have been practical for the users to be running X clients.


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