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| SCHED_DEADLINE v6 released |
| By special contributor cloud on 2012-10-27 01:05:38 |
| A new version of the real-time Linux scheduler called SCHED_DEADLINE has been released on the Linux Kernel Mailing List. For people who missed previous submissions, it consists of a new deadline-based CPU scheduler for the Linux kernel with bandwidth isolation (resource reservation) capabilities. It supports global/clustered multiprocessor scheduling through dynamic task migrations. This new version takes into account previous comments/suggestions and is aligned to the latest mainline kernel. A video about SCHED_DEADLINE is also available on YouTube. |
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| RE[4]: lie-nux at it again. |
| By Alfman on 2012-10-27 19:38:28 |
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Gullible Jones, "What bothers me is that (by default anyway) is that it can be used by a limited user to create an an effective denial-of-service attack." I see your point. You can put hardlimits on a user's disk/cpu/ram consumption, but that can easily interfere with what users want to do. I'm not sure any system can distinguish between legitimate resource usage and accidental or malicious usage? At university some ten years ago, we were using networked sun workstations, I'm sure they'd know something about distributing resources fairly to thousands of users. I don't remember the RAM capacity/quotas, but I do remember the disk quota because I ran into it all the time - soft limits were like 15MB, uck! |
 - Score: 3 |
| RE[5]: lie-nux at it again. |
| By Laurence on 2012-10-27 19:43:12 |
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> what happened to the unix method of copy some program to a directory and just use it ?? That method never existed. Even in the old days programs had to be compiled for each Unix variant and architecture, and these days UNIX dependencies are almost as bad as Linux. Even on Windows, so called "stand alone" applications have pre-requisites, be that a specific version of the .NET framework, the latest DirectX drivers or even just Win32 libraries. > i have 512 megabyte in my desktop ( mint linux ). i have to restart most days. it just hangs. Have you never considered that your problem might be running one of the most resource heavy distributions of Linux on a 10 year old PC? You'd be better off with Puppy than Mint. > i know about computing... i built the first control program ( os ) of south asia, in 2002. it was based on microkernel architecture but ran in x86 "real mode". just a demonstrator. had message passing and unix-like "signals". Please don't insult our intelligence with such blatant lies. If you want to appear to understand this subject, then you're much better off learning the subject (and keeping quiet on the subject until you do) rather than pretending to then covering your tracks with fictitious boasts because everyone has voted you down for posting nonsense. |
| - Score: 6 |
| RE[13]: lie-nux at it again. |
| By Laurence on 2012-10-27 20:03:58 |
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> Package managers may be nice, but not everything is in a repository and even when everything is you can still break the system. Windows and OS X users can't even spell the word 'dependency'. For some reason these "inferior" systems don't have this problem. Of course Windows and OS X have dependencies. What the frak do you think DirectX, .NET, JRE and OpenGL are? To name but a small obvious few. And only last week I ran into an issue where one client couldn't install a Blackberry manager on his Mac because he never upgraded the OS from Tiger. That's one hell of a massive dependency right there. Yeah you could argue that only idiots would try to run java applications without installing JRE, or expect all the latest Mac applications to run a 7 year old version of OS X, but the same could be said for Linux users who choose to run a distro that doesn't properly manage dependancies when they're only a novice. The *buntu's, however, rarely have such issues. So while I do agree that the Linux shared object method kind of sucks at times, these days it's pretty well managed so conflicts only happen about as often as they do on other platforms. Edited 2012-10-27 20:06 UTC |
| - Score: 3 |
| RE[2]: lie-nux at it again. |
| By Laurence on 2012-10-27 20:12:57 |
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> There's a little truth to this. Try running $ dd if=/dev/zero of=~/dumpfile bs=4G count=1 on a system with 2 GB of RAM and any amount of swap space; the OS will hang for a long, long time. (If you don't have swap space, the command will fail because you don't have enough memory. But it's not safe to run without swap space... right?) Mind you, Windows is just as bad about this - it just doesn't have tools like dd preinstalled that can easily crash your computer. :) If Linux gets exhausted of RAM, then the requesting application is killed and an OOE (out of memory exception) raised in the event logs. Sadly this is something I've had to deal with a few times when one idiot web developer decided not to do any input sanitising which effectively ended up with us getting DoS attacked when legitimate users were make innocent page requests. <_< |
| - Score: 3 |
| RE[4]: lie-nux at it again. |
| By Laurence on 2012-10-27 20:16:43 |
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> I realize the above is correct behavior... What bothers me is that (by default anyway) is that it can be used by a limited user to create an an effective denial-of-service attack. Stalling or crashing a multiuser system should IMO (ideally) be something that root, and only root, can do. :P mv `which dd` /sbin/ problem solved. Edited 2012-10-27 20:18 UTC |
| - Score: 3 |
| RE[14]: lie-nux at it again. |
| By MOS6510 on 2012-10-27 20:17:19 |
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> So while I do agree that the Linux shared object method kind of sucks at times, these days it's pretty well managed so conflicts only happen about as often as they do on other platforms. Probably as often as finding users who still use OS X Tiger (and use a BlackBerry) or Windows installs without Direct X or .NET I guess. This in no way compares to the stuff Debian wants to download if you install something. On a server, without GUI, it downloaded X11 + its dependencies because I wanted to install some graphic conversion utility (CLI based!). Removing that tool removes the tool, but not X11. With apt-get dist-upgrade I managed to create non-working or unstable systems. Or wicked situations where X can't be installed, because Y needs to be installed first, but Z depends on it and Z doesn't exist. Windows and OS X don't have package systems that involve dependencies, because it's no big deal. |
| - Score: 2 |
| RE[15]: lie-nux at it again. |
| By Laurence on 2012-10-27 20:38:54 |
|
> This in no way compares to the stuff Debian wants to download if you install something. On a server, without GUI, it downloaded X11 + its dependencies because I wanted to install some graphic conversion utility (CLI based!). That's hardly a fair example given Windows Server and OS X Server all come with a GUI preinstalled. Plus even with X installed, Debian has a lower footprint. So if you want to bitch about having to install a GUI on Debian, then at least appreciate the irony that you're comparing it to two other OS where a GUI is mandatory. > Removing that tool removes the tool, but not X11. With apt-get dist-upgrade I managed to create non-working or unstable systems. Or wicked situations where X can't be installed, because Y needs to be installed first, but Z depends on it and Z doesn't exist. With the greatest of respect, this boils back to my comment about people using a more advanced distro before they're ready for it. If you want to be spoon-fed, then use an appropriately dumbed down distro and leave the enterprise solutions to the sys admins. To be honest I get sick and tired of hearing people say Linux needs to be more like X, Y or Z. The reality is, if I wanted something more like Windows, then I'd be running Windows. The reason I choose to run Linux is because I don't want to be spoon-fed. I want the power to build the system I want, even if that means I could potentially fuck it up completely. And if I do need something quick and painless, then I'm more than happy to throw on a copy of Ubuntu (I've done this in the past when I just needed a working laptop that evening). So if you don't like the way how your enterprise distro let you hang yourself, then I think the bigger issue is why you considered an enterprise level distro to be suitable for your specific requirements. > Windows and OS X don't have package systems that involve dependencies, because it's no big deal. You've never used Windows update then ;) |
| - Score: 4 |
| RE[16]: lie-nux at it again. |
| By MOS6510 on 2012-10-27 20:55:26 |
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> That's hardly a fair example given Windows Server and OS X Server all come with a GUI preinstalled. Plus even with X installed, Debian has a lower footprint. So if you want to bitch about having to install a GUI on Debian, then at least appreciate the irony that you're comparing it to two other OS where a GUI is mandatory. I only complain that some tools require a lot of dependancies, a lot in number and in bytes. Some of which aren't always logical on first (or second) sight. Sometimes you want to check something out, a utility of 23 KB, then 31 MB gets downloaded, the utility doesn't work, you deinstall it and free up 23 KB. But at least we can agree that the GUI isn't really a dependency for Windows and OS X, as they already have one. > To be honest I get sick and tired of hearing people say Linux needs to be more like X, Y or Z. The reality is, if I wanted something more like Windows, then I'd be running Windows. The reason I choose to run Linux is because I don't want to be spoon-fed. I want the power to build the system I want, even if that means I could potentially fuck it up completely. And if I do need something quick and painless, then I'm more than happy to throw on a copy of Ubuntu (I've done this in the past when I just needed a working laptop that evening). I'm not complaining that Linux needs to be more like Windows or OS X, I'm fine with it like it is. My only point is that "dependencies" are much more of an issue than they are on Windows and OS X. No doubt you can find issues with Windows and OS X that aren't so on Linux. When using Windows or OS X I have no package manager that downloads dependencies, nor do I have to do this manually. Apparently I was using a new iMac for some time before finding out it didn't have the JRE. I only noticed because someone wanted to show a webpage with a rotating mobile phone. OS X said I didn't have Java, if I wanted to install it, I said yes and saw a rotating phone. > You've never used Windows update then ;) Well, I have and the only thing I don't like about it that on a new install it says that there are X updates and after installing them and rebooting it turns out there are more updates and after another reboot it again offers some updates. Or sometimes it takes a long time searching for updates only to prompt me that I need to update Windows Update first. Most Windows software just installs and it if needs something extra it will download/install it automatically. |
| - Score: 2 |
| RE[2]: lie-nux at it again. |
| By ParadoxUncreated on 2012-10-27 21:02:52 |
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You`ve been on osnews too long. "Perhaps linux is.." Actually if you have had all three mainstream OS`s installed, say windows XP (which can be made to run quite smooth), OSX (actually slow, sometimes even taking 5s for keyboard response here) and for instance Ubuntu (many would call it a bloated linux, but still), you would actually prefer Ubuntu. So how can linux be badly written? Indeed it seems to be the better of them all. If you wanna talk about badly written, think about the product MS sells. That is all, no enthusiasm, just a dollarmonkey, a product sold, just as cp/m once was. Also junk. I think most enthusiasts agree that windows is POORLY written. And OSX shows that even original unix code, can turn to a windows-like annoyance. Linux though, and Ubuntu, lots of choice. Modular mindset. And the best of code. You wanna run a windowmanager from the time of pre-overobfuscated high-level concepts, try IceWM, with a good theme. And you don`t have to worry about all the desktop-soapopera either. "no desktop id dead" "no desktop is alive" "no linus killed the desktop with evil mentalrays". And here I was running IceWM and not noticing a thing. And Wayland is coming in a big way. "Poorly written" - no. And it has a lot of innovation, and seems to be incorporating more and more of realtime aswell. Have you ever played an openGL game with ACCURATE fps? It is just so much more enjoyable. Not to speak of how lowlatency/lowjitter improves the responsiveness of the desktop, making activity already on the next frame, after input. No "lie", no evil coders. But as many places linux has been associated with several things. And for instance something many people "know" is that Gentoo is for "performance". However it`s mostly a myth, and in their forums you will get some really bizarre answers from time to time. What I suggests is really just trying out the most popular distributions like Ubuntu/Suse/etc. If you`re into realtime, or low-jitter, you might want to build yourself a PC just for that purpose also. I am doing one, and it looks like this currently: http://paradoxuncreated.com/Blog... It`s gonna be great. Peace Be With You. |
| - Score: 0 |
| RE[5]: lie-nux at it again. |
| By jessesmith on 2012-10-27 21:08:29 |
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That just takes care of one tool which can bring the system to its knees, limiting access to dd is a bandage. The issue is that any application on Linux can cause the system a great deal of stress or bring it down. (I do this a couple of times a year by accident.) There are ways to protect against this kind of attack (accidental or not) such as setting resource limits on user accounts. Most distributions do not appear to ship with these in place by default, but if your system requires lots of uninterrupted uptime, the sysadmin should consider locking down resource usage. |
| - Score: 3 |
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