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Linux May Need a Rewrite Beyond 48 Cores
An anonymous reader writes "There is interesting new research coming out of MIT which suggests current operating systems are struggling with the addition of more cores to the CPU. It appears that the problem, which affects the available memory in a chip when multiple cores are working on the same chunks of data, is getting worse and may be hitting a peak somewhere in the neighborhood of 48 cores, when entirely new operating systems will be needed, the report says. Luckily, we aren't anywhere near 48 cores and there is some time left to come up with a new Linux (Windows?)."
Can somebody please explain what the fuck they are actually talking about? They've dumbed down the terminology to the point I have no idea what they are saying. Is this some kind of cache-related issue? Inefficient bouncing of processes between cores? What?
Having read eldavojohn's post that summarizes the article, it appears that the reason to pick out Linux specifically is because that is the OS that the writers of the paper actually tested. Since Windows uses a different system for keeping track of what various cores are doing it is likely that Windows will run into this problem at a different number of cores. However, until someone conducts a similar test using Windows we will not know if that number is more or less than 48.
The truth is that all men having power ought to be mistrusted. James Madison
Core !=CPU
Hahaha. Oh arrogances from ignorance, how I loath you.
The Kruger Dunning explains most post on
We've known about this problem for ... well, as long as we've had more than one core - actually as long as we've had SMP... You increase the number of cores/CPUs, you decrease available memory thruput per core, which was already the bottleneck anyway. Am I missing something here?
Yes, but the submission that got accepted has a bullshit headline.
Of course "Linux May Need to Continue Making Incremental Changes Like It Has Been Doing For The Last Several Years To Scale Beyond 48 Cores" doesn't draw in as many clicks.
Which is why he's treated like shit: Can't have any kind of excellence here, Taco wants to keep that old-school newsgroup feel. That's the only explanation that still fits.
Linux, you magnificent bastard, I read the fucking manual!
Linux supposedly scales to 1024 or something like that. This is not what they supposedly scale to, but the performance impact of actually trying to use that many cores.
The very act of summarization constitutes an act of commentary. You're saying "I think the pertinent parts of this story are these, and the most important questions raised are those."
A good summary invites commentary and frames the questions in a way which makes for better discussion, but don't for a second imagine the OP ought to be value-neutral (if such a thing could even exist.)
DRM: Terminator crops for your mind!
I was kind of wondering about the "modern operating systems" comment... I think he meant "desktop operating systems".
What's a "desktop operating system" these days ? The only mainstream OS that hasn't seen extensive use and development in SMP server environments for a decade plus is OS X. For all the others, "desktop" vs "server" is just a matter of the bundled software and kernel tuning.
Even OS/2 could scale to 1024 processors if I recall correctly.
Yeah. Just like those old PPC Macs were "up to twice as fast" as a PC.
Trolling, I'm sure, but to people who take "GNU/Linux" seriously: how much of any given distro is really GNU code anymore? While GNOME may still be preferred by Ubuntu, there are also a lot of Kbuntu users, and many other distros seem to prefer KDE. Neither XFree86 nor X.Org were ever GNU. Smaller installations, like smartphones and home gateways (which often do run Linux, even if you can't install a custom version like DD-WRT), use busybox for their basic command line tools, and almost certainly do not use glibc. Debian even went for the eglibc fork, partially because Ulrich Drepper makes Theo DeRaadt look like a nice guy. HURD has gone nowhere for 20 years now, even if it does have some neat ideas.
Non-GNU GUI applications and libraries now make up a huge percentage of a desktop distro, Apache and custom web apps make up a big chunk of server code, and smartphones may or may not have any GNU code at all.
So what's left of GNU code now? Well, gcc is likely to keep being the world's de facto C compiler (though even this was mainly because of the egcs fork way back when). I'm sure there will be legions of emacs users for years to come, and I guess a lot of people still prefer GNOME. GNU's basic command line tools and bash will no doubt still be used on servers and desktops. But is this really sufficient to warrant a "GNU/Linux" nomenclature, not to mention all the pedantry that surrounds it?
To the AnonCow troll above: GNU code has nothing to do with how the kernel handles multicore processors, so your whole point is moot within this context.
Not a typewriter
No, I read /. because of comments like eldavojohn's. If they were to disable the comments I'd unsubscribe it from my feeds immediately.
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Debian (and I suppose Ubuntu too) makes use of a lot of Bash scripts behind the scenes. Grub is still the boot loader of choice. A lot of installation CDs use parted to set up the hard drive. Just some examples off the top of my head.
The point isn't that NT Scales to 256 cores, the point is how efficient it is when scaling to this many processors. The NT Kernel in Win7 was adjusted so that systems with 64 or 256 CPUs have a very low overhead handling the extra processors.
Linux in theory (just like NT in theory) can support several thousand processors, but there is a level that this becomes inefficient as the overhead of managing the additional processors saturates a single system. (Hence other multi-SMP models are often used instead of a single 'system')
Just simply Google/Bing: windows7 256 Mark Russinovich
You can find nice articles and even videos of Mark talking about this in everyday terms to make it easy to understand.