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Red Hat Software Linux

Alternative To the 200-Line Linux Kernel Patch 402

Posted by timothy
from the you-go-first dept.
climenole writes "Phoronix recently published an article regarding a ~200 line Linux Kernel patch that improves responsiveness under system strain. Well, Lennart Poettering, a Red Hat developer, replied to Linus Torvalds on a mailing list with an alternative to this patch that does the same thing yet all you have to do is run 2 commands and paste 4 lines in your ~/.bashrc file."
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Alternative To the 200-Line Linux Kernel Patch

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  • There is a right way to do things and a hackish way. I wonder which one is which
    • by h4rr4r (612664) on Thursday November 18, 2010 @06:10PM (#34275920)

      I've done some tests and the result is that Lennart's approach seems to work best. It also _feels_ better interactively compared to the vanilla kernel and in-kernel cgrougs on my machine. Also it's really nice to have an interface to actually see what is going on. With the kernel patch you're totally in the dark about what is going on right now.

      -Markus Trippelsdorf

      right from the article

      • by Weaselmancer (533834) on Thursday November 18, 2010 @06:28PM (#34276136)

        Two things:

        1) There isn't a difference between the kernel patch and the command line hack. They are equivalent. The command line bit was known beforehand because that was the method used to figure out if this kernel hack would be a good idea. The kernel hack just makes the process transparent.

        Linus says: Right. And that's basically how this "patch" was actually tested originally - by doing this by hand, without actually having a patch in hand. I told people: this seems to work really well.

        2) Linus recommends the kernel patch:

        Linus also says:Put another way: if we find a better way to do something, we should _not_ say "well, if users want it, they can do this *technical thing here*". If it really is a better way to do something, we should just do it. Requiring user setup is _not_ a feature.

        Source. [lkml.org]

        • by Anonymous Coward on Thursday November 18, 2010 @06:58PM (#34276536)

          They are not the same. The kernel patch groups processes by owning TTY. The bash shell change groups them by session. Source: http://lwn.net/Articles/414817/ [lwn.net]

          • by by (1706743) (1706744) on Thursday November 18, 2010 @07:24PM (#34276812)
            It seems like a kernel command line option would be a great solution -- it would "just work" for the normal user, and the user with specific needs / servers / whatever could just append the appropriate few characters to the bootloader config.
          • by segedunum (883035) on Thursday November 18, 2010 @09:12PM (#34277678)
            The effect is exactly the same. This is just Lennart trying to hijack another useful development thread and trying to tell us how systemd will solve everything.
        • by SharpFang (651121) on Thursday November 18, 2010 @07:03PM (#34276602) Homepage Journal

          The difference is the kernel patch is 200 lines of C code, which compiles to several kilobytes of machine code. The shell code needs to spawn a bash process upon startup of every other process, that's several megabytes of RAM and interpreting contents of text scripts that perform the operations.

          The final effect may be the same but the overhead of performing the operation is much smaller with the kernel patch.

          • by Geoffreyerffoeg (729040) on Thursday November 18, 2010 @09:03PM (#34277618)

            No, incorrect. This is a modification to your .bashrc, which is (already) run every time you start a bash process, within that process (i.e., not a new process). Nothing needs to be spawned on every single process.

            Admittedly the bash script does spawn some processes, but a) that's the way .bashrc works, and you have dozens of those in there, and b) it's only one process, a mkdir. The echo and the conditional run within bash itself.

            The way that the configuration works, whether done in the kernel or in your .bashrc, is to associate all processes spawned from a single bash shell with a single new scheduling group. This gets you better performance when you're running processes from terminals, by associating logically-similar groups of processes in the kernel instead of letting it see all the processes as a giant pile.

            The intended use case, which is pretty clear from the LKML discussion, is to make performance between something intensive (like a compilation) in a terminal and something non-terminal-associated (like watching a movie) better-balanced.

            • by arth1 (260657) on Thursday November 18, 2010 @10:40PM (#34278226) Homepage Journal

              What I don't get is why he uses

              if [ "$PS1" ]; then

              instead of

              if [ -t 0 ]; then

              Why the latter? Because it works, that's why:

              # sh -c '[ "$PS1" ] && echo tty detected'
              #

              # sh -c '[ -t 0 ] && echo tty detected'
              tty detected

              The other way around, if a user has set PS1 in .profile, you'll get false positives, and cron jobs that will consume more than their fair share of resources.

              • by Anonymous Coward on Friday November 19, 2010 @05:16AM (#34279678)

                One never sets PS1 for non-interactive shells, and it's the primary way the shell tells the user's startup scripts whether they're interactive. There's a good chance the PS1 method spares a system call, too :-) It's also what the documentation says to do.

                Your [ -t 0 ] approach also fails in cases where an interactive shell is being run on a non-tty. Although almost any shell since about 1990 tends to complain in such cases, at least the PS1 method will still run the right .profile code, and the -t method will not.

            • by Bloem (528155) on Friday November 19, 2010 @12:43AM (#34278772)

              I've read your comment several times and each time I hear the voice of comic book guy from the simpsons in my head. I'm not trying to be rude so I'm hoping you're not offended by this. I think it has to do with the "no, incorrect" part that your comment starts with.

    • by spun (1352) <loverevolutionary&yahoo,com> on Thursday November 18, 2010 @06:19PM (#34276028) Journal

      One requires a kernel patch. One uses functionality already present in the kernel to do the same thing. Testing reveals the one that doesn't require a kernel patch is more responsive. You tell me which is best.

      • by tepples (727027)

        You tell me which is best.

        Best would be if the operating system distributor (Canonical, Red Hat, etc.) were to include the one that doesn't require a kernel patch in the next version of the operating system.

      • by clockwise_music (594832) on Thursday November 18, 2010 @07:59PM (#34277138) Homepage Journal
        Best for you right now? Update your .bashrc file.

        Best for all the people who miss this little nugget? Include it in the kernel.
        • Re: (Score:3, Informative)

          by TheRaven64 (641858)
          The stock .bashrc on most Linux systems includes /etc/bashrc. On the recent systems I've looked at, this then includes /etc/bash.d/* (or something similar). You can get the same effect as adding this to every single user's .bashrc by simply dropping a file with the magic lines into /etc/bash.d/. A package can do this and you don't even need to reboot for it to take effect. Best, it's trivial to turn off for systems where it's not applicable.

          So, which is a better approach?

    • by Carewolf (581105)

      I think my computer just reached a load of 100.3

      Browsing slashdot just fine. Back to watching fullscreen youtube videos... for science, of course!

    • by gilesjuk (604902)

      Probably the Red Hat one, after all they probably know more about which values and settings to tune up than anyone.

      They probably have a lot more of these, but it's a competitive business and they'll keep them secret to have an advantage over the competition.

    • by neiras (723124) on Thursday November 18, 2010 @07:59PM (#34277140)

      The kernel patch is the hackish way to do it. They're hard-coding policy settings into a kernel patch. Dumb. The kernel is there to provide the knobs, not to twiddle them for you.

      Lennart's argument is that policy should not be hard-coded into the kernel. He's not saying "everyone should do this in a bash script". He's saying "leave policy settings to userspace mechanisms that can handle them better." Say, systemd for instance.

      Users would be better served by Lennart's approach, I think.

      Funny thing is, most desktop users will not see the benefits of the patch, since most of them never use the terminal to run cpu-hogging kernel builds. All desktop apps share the same cgroup.

      That won't stop hordes of n00bs from claiming ZOMG MAI SYSTEM IS SO MUCH FA$TER NOW OMG!

  • Any linux kernel? (Score:3, Interesting)

    by w0mprat (1317953) on Thursday November 18, 2010 @06:08PM (#34275884)
    Will this work on more than just x86, for example a rooted Android phone? I might try this now.
    • Re: (Score:2, Informative)

      by Anonymous Coward

      Yes, because is has to do with the way the kernel handles multitasking.

      • Re: (Score:3, Insightful)

        by willy_me (212994)
        But I was under the impression that Android devices already utilized a different scheduler. In addition, phones have different requirements - for example, some might require a real-time kernel in order to operate on a cell network. Long story short, messing with the scheduler could have serious repercussions on an Android device. Only those who really know what they are doing should attempt it. The rest of us should simply wait - unless you don't care if your phone is reliable or not.
        • Re: (Score:3, Interesting)

          by NuShrike (561140)

          For the Qualcomm Android platform and generally most smartphones, the radio stack/base-band/etc on a different processor running a RTOS. Makes it really hard to hack too.

          It is quite safe to mess with the scheduler for the "user" application processor.

  • Can anyone explain how the bash script / commands work? I know a fair bit about Linux but frankly this goes into device mappings at a level I've rarely had to deal with.
    • Looks like an alternative solution is already there in the Kernel. The commands just switch it on.

    • by greg1104 (461138) <gsmith@gregsmith.com> on Thursday November 18, 2010 @06:31PM (#34276196) Homepage

      It makes every process spawned by the user that passes through the bash shell add their process ID to a per-user task control group. See the documentation on control groups [mjmwired.net] for more information about exactly what that means, and what what some of the commands involved aim to do. I'm not sure if this is exactly the same impact as the kernel-level patch, which aimed at per-TTY control groups. That might includes some processes that don't pass through something that executes the .bashrc file along the way.

    • by MBCook (132727) <foobarsoft@foobarsoft.com> on Thursday November 18, 2010 @06:37PM (#34276292) Homepage

      The kernel has a mechanism to schedule groups of processes, and it has for years. By grouping tasks together, you can make one process (video playing) get the same cpu share as a group of processes put together (compiling code). By doing this (instead of the video processing being equal to just one of the compiling processes), everything feels more interactive, even though it's actually slightly slower.

      No one uses scheduling groups because they have to be setup by root and it's not the easiest thing in the world (you have to write stuff into sysfs, I think). No distributions set them up.

      The magic kernel patch just adds a simple rule to the scheduler. When a process starts, it goes into a group with the rest of the processes in that TTY (virtual terminal). This means the user doesn't have to do anything and the groups are setup automatically.

      Poettering thinks this is somewhat hackish, and that things shouldn't be based on what TTY a process is started on. He made the little script to prove that this can easily be done in userspace.

      Linus has rejected this, basically saying that we've had years for people to make something like this and no one did until the kernel patch came along. The patch is simple, reasonable, and doesn't require distributors to ship updated userland files to put processes in groups.

      I should note that my understanding comes from LWN [lwn.net], which has had excellent coverage of this on their kernel page, as always. You'll be able to see their articles in two weeks if you're not a member (which is worth it if you like this kind of stuff).

  • old-school (Score:3, Funny)

    by MagicM (85041) on Thursday November 18, 2010 @06:15PM (#34275972)

    I heard that if you stick a penny to the top of your case it speeds up everything by 200%.

  • by joeflies (529536) on Thursday November 18, 2010 @06:15PM (#34275974)
    this is definitely one of those things that I add now, then forget about later, and it becomes a condition that may or may not work when I apply upgrades & patches in the future. Whether or not the .bashrc approach is faster, I think that going down the kernel route makes it more consistently usable.
    • by Trepidity (597) <delirium-slashdot@@@hackish...org> on Thursday November 18, 2010 @06:18PM (#34276010)

      True, though it could be done at the distro level, which appears to be the author's plans (the person who wrote this script works for Red Hat, and discussed elsewhere in the thread what Red Hat's plans are for rolling out systemd [freedesktop.org], which will handle this). Then things would be appropriately updated by the maintainers rather than relying on users to keep their .bashrc synced with infrastructure changes.

      • by Shimbo (100005) on Thursday November 18, 2010 @06:54PM (#34276494)

        True, though it could be done at the distro level, which appears to be the author's plans (the person who wrote this script works for Red Hat, and discussed elsewhere in the thread what Red Hat's plans are for rolling out systemd [freedesktop.org], which will handle this).

        Indeed. "Should we be punting this for userspace tools to handle?" isn't the same question as "should we punt it to the user?".

      • Re: (Score:3, Funny)

        by Psychotria (953670)

        True, though it could be done at the distro level, which appears to be the author's plans (the person who wrote this script works for Red Hat, and discussed elsewhere in the thread what Red Hat's plans are for rolling out systemd [freedesktop.org], which will handle this). Then things would be appropriately updated by the maintainers rather than relying on users to keep their .bashrc synced with infrastructure changes.

        I understand what you're saying and agree. The problem I have is with your userid. 597. Users with IDs as low as this are mythical. Kind of like unicorns or maybe even grues; they are creatures of the imagination. Users with sub-1000 user ids are DANGEROUS. They say stuff that most often makes sense and this can be mesmerising. They do this to lure us into the trees to have intercourse with sirens of the forest, I have heard. Your post is an incredible example of the delirium that can ensue when magical bei

  • by Lemming Mark (849014) on Thursday November 18, 2010 @06:19PM (#34276026) Homepage

    My understanding of the original kernel patch is that it just puts stuff from different ttys into different groups for scheduling purposes so that they're less able to hog each other's resources. This alternative just makes your shell sort it out itself when it starts i.e. when you're running a new terminal. So this should basically be equivalent.

    See this comment from the latest article for Linus' take on putting this stuff in-kernel:
    http://www.webupd8.org/2010/11/alternative-to-200-lines-kernel-patch.html#comment-98834842 [webupd8.org]

    The comment here is very important to remember though:
    http://linux.slashdot.org/comments.pl?sid=1870628&cid=34241622 [slashdot.org]
    another comment on that article (which I can't now find - anybody know where it is?) basically said that the patch suits Linus's own use of compiling kernels whilst surfing the web. Sounds like a reasonably accurate assessment really so for now it's far from the magical boost to general interactivity some may have hoped for. In some sense there's no such thing anyhow.

    Nonetheless the comment linked above also has Linus talking about increasing the scope of the automatic grouping heuristics in the future so hopefully the "just works" nature of this should become available to more people eventually.

    The original kernel patch (and this alternative) aren't magically making everything respond better, they just improve certain usecases.

  • by Anonymous Coward on Thursday November 18, 2010 @06:22PM (#34276050)

    Poettering wants scheduling to be handled by his "systemd", a replacement to init/upstart. This, by the way, is the developer of Pulseaudio, so those of you who've experienced broken sound in recent years can now look forward to broken system initialization, coming soon to a Linux distribution near you...

  • Whee... (Score:5, Funny)

    by Target Practice (79470) on Thursday November 18, 2010 @06:27PM (#34276124)

    Man, after reading some of that thread, those folks in kernel development make Slashdot users seem downright well-mannered.

    • Re: (Score:3, Insightful)

      by Pharmboy (216950)

      You want to see some real, over-the-top rudeness? Go to a forum designed to help Linux newbs.

      I've been tooling with Linux for 15 years now, so used to the arrogant "help" found in many forums and groups, but I've had non-Linux friends check some out and were completely amazed at the average level of rudeness in the average "help" reply. It certainly didn't make them want to jump into Linux when that is the average help. For obvious reasons, half the admin-types on Linux forums remind me of the comic book

      • Re:Whee... (Score:5, Insightful)

        by gandhi_2 (1108023) on Thursday November 18, 2010 @07:44PM (#34276966) Homepage

        Ever seen a 50-year-old ER nurse? 90% of the time, they are callused to the suffering around them. It comes with repeated exposure to the environment, and although their demeanor may seem rough to others, they are extremely efficient and skilled.

        Sometimes, I think what some mistake for IT snobbishness is just a natural consequence of exposure to the lifestyle.

        I thought it would be fun to post some things in answers.yahoo.com in the IT-ish categories... after a while you realize that the REALLY good questions are drowned out by people who REALLY just need to GTFO and RTFSomething.

        I work in public ed IT, and can say with NO uncertainty that most people don't want the right answers, they want the nice answers. It's hard not be rude in some cases.... it just comes out your pores after enough exposure to the environment.

        • Re: (Score:3, Insightful)

          by Pharmboy (216950)

          Ever seen a 50-year-old ER nurse?

          You are right in that many people are inadvertently (or apathetically) rude for the purpose of efficiency. "I don't have time to be nice, I'm busy helping sick people, and being nice slows me down." While it makes them efficient and effective at the technical skills (things that CEOs love) it doesn't necessarily make them the best care givers. Outside of actual life and death emergencies (and your ER example would be excempted), how care is given is as important as the ca

        • Re: (Score:3, Insightful)

          by adisakp (705706)

          Ever seen a 50-year-old ER nurse? 90% of the time, they are callused to the suffering around them. It comes with repeated exposure to the environment

          So the people who are good at Linux treat the noobs like shit because they calloused from all the pain they've suffered? That's hardly a ringing endorsement for Linux if using it long enough to become a proficient user makes you as shellshocked and numb as someone working in a triage unit.

        • Re:Whee... (Score:5, Insightful)

          by vegiVamp (518171) on Friday November 19, 2010 @03:17AM (#34279268) Homepage

          This.

          I'm on a few mailinglists, and while I do my best to provide clear, concise, correct and helpful answers to questions, I keep being amazed at how some people simply don't bother to do the basics first. Like, you know, even looking in the general direction of the manual.

          One of the lists I'm most active on these days is the MySQL one, given that I'm almost fulltime DBAing these days. Note that MyQSL has excellent and comprehensive online manuals for every version you care to run.

          I've seen people actually think that list is populated by MySQL employees who are paid to answer their every stupid question, and get impatient and testy if they haven't seen an answer in ten minutes.

          i've seen people spam the list with first their inane RTFM questions, followed by a great big stream of "insights" on how he solved it and the most obvious straight-from-the-manual statements.

          I've seen people who seem to think that the list is there to write their queries for them. After I got rather miffed and wrote a bit of a sharp mail at one of them about basic manners, what the list is for, how to ask questions properly and what to do before you even think of asking the list; that guy now consistently does his homework, tries to work it out for himself and if he really doesn't find it or wants another opinion, politely puts the question to the list in a clear and concise way. Of course he now gets all the help he needs, and he's even put a few quite interesting things to the list in the mean time. He has, interestingly, also taken to calling me 'Sir' whenever he asks me a question. I never asked for it, but I have to admit I kinda like it :-)

          Sometimes it's necessary to make it quite clear to people what they can and cannot expect from online help, and how to behave there. This used to be perfectly acceptable, but since Eternal September began, the flood of ignorance has gotten so vast that I can fully imagine it can sometimes be hard to remember actually helping people in the middle of all the stupidity.

      • Re:Whee... (Score:5, Insightful)

        by bmo (77928) on Thursday November 18, 2010 @07:44PM (#34276978)

        I get rude when people expect Linux to be Windows after about the third time they complain about where the control panel is (among other things) and when they're simply trolling. It's amazing the amount of trolling going on in the help forums. Sometimes it extends to irc.

        Car analogy follows:

        "Gee, this BMW is nothing like my Ford." "Why is the battery in back again?" "They should put the battery in the engine compartment" ("but it's there for weight distribution") "I don't care about that, it's stupid"

        It's not Windows. It's not a cheap Windows. It's not anything like Windows. Stop expecting it to be Windows. Once you do that, a lot of things become _much_ easier.

        --
        BMO

      • Re: (Score:3, Insightful)

        by Knuckles (8964)

        I've been using Linux for 15 years too and I have never seen that. I don't know where you people go to have such bad experiences. OTOH, the Windows forums I sometimes stumble into via Google are usually full of clueless guys and devoid of actual help. Granted, Windows is opaque, but still.

      • by Artemis3 (85734)

        This was fixed in 2004, with Ubuntu's Code of Conduct. Telling people RTFM is forbidden, either you help or shut up. People sometimes wonder whats the big deal with Ubuntu, and I'm positive this is one of the main reasons. You can check the forum http://ubuntuforums.org/ [ubuntuforums.org] or hop to Freenode's #ubuntu channel to see this policy in action. No matter how repeated or simple a question is, it is allowed and if you reply, it is to help, even if thats pointing someone to a well written help page (like the many at h

  • by mister_playboy (1474163) on Thursday November 18, 2010 @06:32PM (#34276206)

    Following the instructions for Ubuntu as detailed in the post will give you an error message everytime you open gnome-terminal.

    One of the comments left by Ricardo Ferreira on that page solved my problem (after rebooting again):

    Edit your rc.local file with sudo gedit /etc/rc.local and delete the following line:

    echo "1" > /dev/cgroup/cpu/user/notify_on_release

    Save and exit gedit. Then, run gedit ~/.bashrc and add the following inside your if statement:

    echo "1" > /dev/cgroup/cpu/user/$$/notify_on_release

    So it should look like this:

    if [ "$PS1" ] ; then
    mkdir -m 0700 /dev/cgroup/cpu/user/$$
    echo $$ > /dev/cgroup/cpu/user/$$/tasks
    echo "1" > /dev/cgroup/cpu/user/$$/notify_on_release
    fi

  • The linked web page doesn't really explain what's going on. For someone who uses Unix but is far from an expert, can someone describe what's going on and why this is cool? Does it even matter if you're not into deep kernal stuff?

    • by icebraining (1313345) on Thursday November 18, 2010 @07:01PM (#34276566) Homepage

      Imagine you have an app that launches just one process, like a music player, and an app that launches 3 (for example, Firefox, which launches a new one for each plugin).
      Since each process has the same priority, the second app - firefox - will effectively have 3x more CPU time than the media player, and possibly stutter the music.

      The kernel has something called cgroups, which enables more than one process to be grouped, and each group will have the same CPU time. So the group (Firefox+plugins) would have the same CPU time than the media player.

      This kernel patch and terminal code enables each terminal you launch to have a different group, so if you launch Firefox from one terminal and the music player from another, they'll have different groups.

    • by Tacvek (948259) on Thursday November 18, 2010 @07:15PM (#34276694) Journal

      Sure.
      Hopefully you know what a TTY is, but in case you don't it it a virtual or real terminal. When you open up an xterm you create one. If you don't have x-windows installed, you reach one, etc.

      Well Linus had an idea about using a grouping functionality that was already in the Kernel to allow all the processes (technically actually all the kernel threads) running from one TTY to be grouped together for scheduling.

      The result of that is that if you are running 99 processes in one xterm that could consume all of your CPU, and you open another xterm, one one just one process that wants 100% CPU, each xterm's processes gets 50% of the CPU, rather than one getting 99% and the other getting only 1%.

      But lets say you only had that first xterm. Since each of those processes are not getting nearly the processor amount they desire, normally the scheduler sees them as nearly starved, and the next process that only wants 5% of CPU does not get much preferential treatment for giving up most of it's time. However, with the grouping, the scheduler can see that those 99 processes are related, and they are not really starved, since as a group they are getting 100%. So now when this other app that wants only 5% comes along, the scheduler might give it pretty much all of that 5% rather than the mere 1% it would have been getting before, and so that app (probably a web browser or something) remains nice and responsive.

      That is not 100% accurate, since I've simplified some things a little, especially with regard to the working of the scheduler, but it should give you the idea.
      Eventually, more heuristics might be added, so that a GUI application that launches a bunch of threads and hogs the CPU might have all it's threads grouped, so they don't hurt responsiveness of interactive apps either.

  • With my new 100/100mbit broadband, and the fastest SSD, and this hack, I'm not sure I'm noticing anything ;O

  • by ras (84108) <russell-slashdot@stuar t . id.au> on Thursday November 18, 2010 @11:25PM (#34278478) Homepage

    An early comment on LWN [lwn.net] captured the technical argument best, I think, which I guess illustrates both the quality of the articles and posters on LWN. The background to this is we are discussing CPU scheduling. If you don't know what CPU scheduling is, think of it as form of mind reading. I'll illustrate.

    Lets say you have asked your computer to do several things, in fact so many that if it follows the usual method of simply dividing its time equally between them it is going to annoy you. The video you watching might start flickering, or the music you are listening will drop out. So obviously the computer must now give more CPU time to playing your movie and less to whatever background task you started, such as that MP3 transcode of your 20,000 song library. Except how is the computer is supposed to know this? This is how we get to mind reading.

    The hack we are discussing is essentially the discovery of a way to read the minds of one particular type of computer user - the Linux Kernel developer. The Linux Kernel developer is in the habit of starting huge background jobs called kernel compiles. These kernel compiles take a looong while, so the kernel developers, being very clever people, have invented all sorts of ways of speeding them up. One of those ways is to divide the task into lots of little bits, and then fire off separate tasks to do each. This takes maximum advantage of available CPU cores, soaking up every skerrick of available CPU time. This naturally enough leaves none left over for other important tasks like watching a movie while waiting your kernel compile. In this particular case the default CPU scheduling strategy of giving each task an equal share of CPU is woefully poor, because there might be 20 kernel compile tasks and just one movie watching task, so the movie player ends up with 1/20 of the available CPU time. This isn't enough to play a movie.

    The mind reading trick discovered boils down to this: Linux Kernel developers use the linux command line interface to fire off the kernel compile. And it turns out that for years now the kernel has been able group the tasks started from a command line and give that group a single portion of CPU time, as opposed to a equal portion to each task in the group. Thus you only have to split up the CPU time into 2, one portion going to the kernel compiler group and the other going to the movie player. Naturally enough the movie player works real well with a 50% allocation of CPU, and so we have a happy kernel developer.

    Now we come to the merits of the two hacks. They both do the job I just described equally well. The difference between them is that one, the kernel patch, is automagic, meaning it happens automatically without anybody having to lift a finger. But it comes at the expense of bloating linux kernel a tiny bit, even for users who won't benefit from it. The other way currently has to be done applied manually using a process the vast majority of Linux users will at best find difficult, tedious and error prone.

    Seems like a simple decision eh - lets take the tiny bloat hit and not inflict our long suffering desktop users with yet another Linux user-unfriendly idiosyncrasy. But here is the rub: it doesn't help them. In fact, for some it might have a negative impact (a gstreamer pipeline started from the command line strings to mind). The people who will benefit from this are the ones that use the command line heavily and regularly. People like Linus. Which is why he liked it so much I guess. But these are precisely the people who will have no absolutely no trouble doing it the manual way.

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