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SuSE and Siemens Release Linux Memory Extension

Posted by CmdrTaco on from the and-it-shows-up-on-excite dept.

hussar noted that SuSE and Siemens have developed a memory extension that will allow Linux to use up to 4GB of memory. Linus has reportedly approved its inclusion in kernel 2.3.15. The strangest part is excite has taken to posting about Linux Kernel Patches. Pretty crazy stuff.

26 of 150 comments (clear)

  1. Re:Excite covering kernel patches by jpranevich · · Score: 2

    Hello,

    Yes, it was key to supporting IRIX. :) In the right crowds, I'm sure that's an important feature. :)

    What's important to note and understand is that everyone, and I mean EVERYONE, has a differnet idea of what is and isn't a good feature. And believe me, I get a fair amount of feedback on my articles and I rarely can please everyone. There's always the person that just isn't happy until the PC internal speaker is supported, or until the kernel can do ISA PnP (it can now), or until it can do some other completely bizarre task that seems trivial to us at first, but them you realize how critical this can be under /just/ the right circumstances.

    That's what makes Linux great: we have such a selection of great things that we have to please everyone a little; but we'll never please everyone entirely.

    As for me, this 4G thing seems pretty silly. :)

    Joe

  2. ...absolutely not! by MenTaLguY · · Score: 2

    Part of the FreeBSD kernel are actually under GNU...

    Most certainly not!


    Berlin-- http://www.berlin-consortium.org
    --

    DNA just wants to be free...
  3. Re:Excite covering kernel patches by orabidoo · · Score: 2

    yep. for all the fears people had (and FUD that got spread) about the commercialization of Linux, here we see the Open Source (and specifically the GPL) magic working just right. Large companies like Siemens suddently find it (financially) worthwhile to contribute to an open project. this is a huge ball that got rolling; it's not just a bunch of hackers competing with MS (and Solaris and ...), now it's large companies and their resources, too. and to think that some MS drone was quoted saying that "the linux hype has peaked" just a few days ago... boy he's in for a surprise :)

  4. Re:this is how companies work by Anonymous Coward · · Score: 2
    I didn't know that P6's had 36-bit memory addressing...

    Yes, P6's have 36-bit physical memory addressing; this does not mean that virtual (linear) addresses are 36 bits. (Some other 32-bit processors, e.g. 32-bit SPARC processors or processor modules with the SPARC Reference MMU, also supported more than 32 bits of physical address. Heck, PDP-11s with MMUs often supported either 18 or 22 bits of physical address, even though they only supported 16 - or 17, sort of, if you count split I&D space - bits of virtual address.)

    Does *any* OS take advantage of this currently???

    Dynix, on Sequent's servers, might - they support much more than 4GB of physical memory, and if the NUMA part of "NUMA-Q" just means that accessing "other people's" memory is slower, not that you have to play bus-mapping games to get at it, they may use the 36-bit features to do that - although I thought I saw something indicating that some of their machines supported 128GB, which requires 37 bits.

  5. Excite covering kernel patches by Nemesys · · Score: 3
    This is another of those tiny little telltale signs that the media has been won over. This story shows they even seem to "get" the kernel development process. However, they're putting it in terms that the mainstream can understand: Big computer company Siemens helps littler Linux computer company SuSe to write an extension for Linux. Kernel boffin also cooperating.

    My best example of this was when I saw a rehash of Pravenich's 2.4 kernel thing on a tech news site - they'd duplicated his mistakes, and were brainwashing the masses with the stuff! ;)

    1. Re:Excite covering kernel patches by SoftwareJanitor · · Score: 2

      As for me, this 4G thing seems pretty silly. :)

      For probably 99.9% of people, it is pretty silly. Most people/companies can't afford that much memory even if they had a motherboard that could handle it (most motherboards are limited to somewhere between 512M and 2G). This limit matters strictly for the very highest end 32 bit systems.
      I think it is mainly being done to eliminate one of Microsoft/Mindcraft's 'checklist' items, and there is certainly a level of justification for doing that sort of thing.
      However, there is also always that 0.1% that it really does matter to, I guess. In general, I would imagine that this probably just won't matter to most of us, but it will remove one of the percieved barriers against high end Linux deployment.
      The difficult thing may be getting people/press to realize that things have changed. Witness the ongoing examples of people who still claim that Linux can't support multiple CPUs at all, when it has had at least rudimentary SMP support for quite some time. And of course they would never mention that Linux SMP support has improved some recently, and is going to be improving further in the next couple of major kernel versions.

    2. Re:Excite covering kernel patches by bmarklein · · Score: 2
      Actually, Excite didn't "cover" this, Siemens & SuSE released a joint press release over BusinessWire, and Excite just passed it along, as they probably do with everything that comes over BusinessWire.

      Maybe it's interesting that Siemens would consider a kernel patch significant enough to warrant a press release, although this doesn't seem surprising to me. It's a pretty significant new feature.

  6. Re:What limit have other OS-es? by pberry · · Score: 2

    The current MacOS can access up to 1.5 gigs (even thought the new high end G4s will let you put 2 gigs in).

    I thinkNT will let you access 4 gigs. At least that is what I understood from the whole Midcraft fiasco...

    I'm not familiar enough with the others to answer...

    --
    -- Are you an EFF member yet?
  7. this is how companies work by Chaostrophy · · Score: 3

    A big company does something, they send out a press release. Nothing new there, it is just that it is about Linux.

    Now, that someone has come up with a bigmem patch that Linus will live with, THAT is news!

    This is a big deal for some users. A real shocker will be if someone comes up with a patch to use the 36 bit addressing on the P6 cpu, for up to 64GB ram on Intel machines.

    --
    Plato seems wrong to me today
  8. Re:What limit have other OS-es? by Guy+Harris · · Score: 3
    what's the point of giving 2GB to the OS?

    I'm not sure, given that the "enterprise" edition lets it use only 1GB, but note that this is virtual memory, not physical memory - this doesn't mean NT is consuming 2GB of physical memory.

    and using almost half of your machine's memory as page cache (in Linux terms, I'm sure NT has an equivalent that's calle dsomething else)

    I infer from the stuff I've seen in the "Inside Windows NT" books that it has a common page/buffer cache; the first edition of Inside Windows NT says

    8.1.2.4 Mapped File I/O and File Caching

    ...

    ...When a thread opens and uses a file, the file system tells the cache manager to create an unnamed section object and maps the caller's file into it. As the caller uses the file, the VM manager brings accessed pages into the section object from disk and flushes them back to disk during paging. ...

    which is similar to what some UNIX systems (e.g., SunOS 4.x, SVR4-based systems, FreeBSD, etc.) do; I have the impression that if the Linux kernel doesn't yet have a unified page/buffer cache in a stable kernel, it's going into the 2.3[.x] line.

    Most of memory is, in effect, a page cache on these systems, unless you count only pages not currently being used as cached, in which case most of memory not used by pages currently being used is a page cache. In addition, the buffer cache (in the sense of the cache of pages read in from files) is just part of the page cache.

  9. Linux kernel story not unusual for excite by Surak · · Score: 2

    Its not unusual really. It fits into excite's usual MO.

    For the non-journalists/editors in the crowd, I'll point out that this story was A) from a newswire service (check the DATELINE--ITS IN ALL CAPS LIKE THIS) and B) the story was obviously a press release (witness the "About SuSE" section of the article -- an obvious shameless plug for the company putting out the press release).

    Excite's news section consists almost entirely of newswires because its cheaper than writing your own stories and they generally don't require too much editing (because they are written by professionals who know what newspaper editors like to see in an article in terms of structure, content, syntax etc.)

    FWIW, I used to design/edit/publish several newspapers for non-profit veterans groups like the AMVETS and PVA...at least until I got a "real" job in the IT field. :)

    --
    My journal has hot /. gossip.
  10. Kernel development driven by people by kijiki · · Score: 3

    I find it somewhat telling that the article didn't mention Andrea Arcangeli and Gerhard Wichert, workin at SuSe and Siemens respectively and wrote this patch pretty much dual-handedly. I suppose with the corpratization of linux, the companies are more important now than the actual people who make linux what it is. At the very least, a link to Andrea's archived message on l-k would give credit where it is due.

    1. Re:Kernel development driven by people by http://i.am/m.luca · · Score: 2

      Agree, this is the lkml announce :
      http://boudicca.tux.org/hypermail/linux-kernel/199 9week34/0442.html

      Rob make an "Update" and give credit to people behind those companies.

      For Italian people: Andrea will talk in Padova check http://meeting.pluto.linux.it/ for more

  11. And then there's SGI. by Espressoman · · Score: 3

    This is great work. Just think what will happen when the SGI big memory project is ready. Check out http://oss.sgi.com/projects/bigmem/. Wow. Two big memory solutions. I just don't know which to choose. Oh. Hang on. I don't have four *fricking* gigabytes of RAM....

  12. Contributions from hardware vendors by cksmith · · Score: 3
    I think this is yet another example of how excellent the open source model is:
    • The hardware vendor gets to show off their hardware.
    • The hardware vendors gains some purely positive publicity and goodwill from the community
    • Everyone else benefits from the contribution.
    Plus, a significant contribution can be merely the seed for further developments, since anyone in the world can read the patch and contribute their own. It's a win-win situation all around.
  13. Re:36 bit and 32 bit by Guy+Harris · · Score: 3
    Logical addressing (program addresses) is still limited to 2GB or 3GB or whatever. So if you put 64G on your quad Xeon factory heater (tm), programs still max out at 4G.

    True, in the sense that at any given instant of time, the linear address space of a process can be no larger than 4GB (and, as segmented addresses get translated to 32-bit linear addresses before being run through the page table, segmentation doesn't help).

    However, as I noted in another post, a process could, if the OS lets it (and most OSes you'd run on big machines do, these days), map stuff into and out of its address space, and more than one process could exist on the machine, so you can use it for userland code, userland data, kernel code, kernel data, mapped files, buffer cache, whatever, just as you can use the first 4GB - it's just a question of what the OS does or lets applications do.

  14. Clarification by Hasdi+Hashim · · Score: 3

    Just a quick note to everybody. It is not about being able to use 4GB of physical memory. It is to enable process to use more than 2GB of memory. Traditional Linux memory model to is split the lower half for kernel memory and upper half for user memory. To check if the pointer is pointing to a kernel memory you just need to check its MSB.

    test %eax,0x8000000
    je user_mem_label

    I think they have worked on 3GB prior to this. SOrry, been a while since I checked the kernel lists.

    Anyhow, this is only of practical use to database developers. maybe some but not many. In any case, you might as well use a 64-bit architecture.

    Hasdi

    1. Re:Clarification by rguenth · · Score: 2

      You are completely wrong with this.
      The issue is not to enlarge the virtual address space of a process, but to enlarge the total probable physical memory to the kernel. The processes still do see only 3GB of virtual memory.
      The difference is, that previously all physical memory had to be mapped into the kernel virtual address space (hence max. 3GB and then 1GB virtual memory to processes), now this is no longer true. Now we have two sorts of memory, normal memory that is always mapped into the kernel virtual address space and the high memory (all above 3GB but to have 3GB virtual address space to processes its usually all above 1GB) which is mapped on-demand to a special virtual address range in the kernel (which is also the overhead of this model).

      Richard.

  15. Re:windows98 by quade]CnM[ · · Score: 2

    Well, from expearance, win 98 wont be stable with 1 gig. I once put 512Meg in a Win 98 system (we had 4 128M DIMMS at the shop, and I just wanted to see). Strange things started to happen, it blue screened quite a bit. It wasn't prity. I would say that you could stick 4 Gigs in a 98 machine, but it wouldent stay running for more then 5 minutes.

  16. Somewhat related question: by Ross+C.+Brackett · · Score: 2

    Could somebody explain to me how (or perhaps why) some of the top-of-the-line Intel-based servers claim to support even more than 4 Gigs of ram? The page for the new IBM Netfinity 8500R, for example claims that it supports "Up to 16GB ECC SDRAM". How is that even possible, since I thought 32-bit architecture made 4 Gigs the max addressable limit, period. Am I wrong? Are they simply selling a capacity nobody can use? This has confused me ever since I first heard about it.

    Thanks.

    1. Re:Somewhat related question: by tjrw · · Score: 5

      You are confusing the virtual and physical address spaces.
      The Intel P6 line has a 36bit physical address bus allowing the chip to address up to 64GB of physical memory. However, since it is a 32-bit processor, you can only see 4GB of this memory at any time. You can change what you can see by playing games with PTEs (page table entries), and/or segment registers.
      To address >4GB of memory requires use of either wide (64-bit) PTEs, or the strange mode Intel added to the PII, that allows large pages with narrow PTEs.
      The Sequent Dynix/ptx OS supports up to 64GB of physical memory. The hard part is conserving enough kernel virtual address space.

    2. Re:Somewhat related question: by rhdwdg · · Score: 2

      4 Gigs the max addressable limit in a flat space, not period. Otherwise we wouldn't have seen more than 64K on 8086/80286 machines, either. In both cases the CPU has more memory addressing pins than bits in registers: 16-bit registers, 24-bit addressing on the 286; 32-bit registers, 36-bit addressing on the Pentium Pro, II, and III. In both cases Intel uses segmenting to push a cheaper technology to grow a little bigger because the next platform is going to arrive far too late.

      The (impossible?) trick is to make segmented memory access "clean". Neither Linux nor *BSD has chosen to embrace the hoops needed to use large memory P6 machines. NT doesn't get full advantage of >4G either, you know: that RAM does have a 32-bit string attached. Offhand I don't know about Solaris, SCO, or anyone else. I'd be a little surprised if Sun didn't do it, although I'd also understand if they left it out to encourage UltraSparc sales.

      The K5, K6, K6-2, K6-3, M2, C6, et al have no such extensions, of course -- just Intel's patented P6 processors and buses.

  17. Re:What limit have other OS-es? by gravious · · Score: 2

    NT 4GB, giving 2GB each to userspace and OS. Enterprise NT allows memory intensive boxen to be configured 3GB for apps and 1GB for the OS. blah. don't know about geography or any other OS.

    --

    Satan, oscillate my metallic sonatas.
  18. Top 5 Reasons by meersan · · Score: 5
    Top 5 Reasons Microsoft Is Glad Linux Will Support up to 4G of RAM

    5) Office 2000 memory requirements now supported by Linux, making port much easier.
    4) Enhances sales potential of Windows 2000 -- WINE now able to run W2K under Linux.
    3) Yet another fun Linux feature to deny and obfuscate.
    2) Can complain before tech-unclued journalists about Linux's memory requirements -- 4G compared to W2K's 128M.
    1) Now that Linux supports 4G of RAM, it will be competition on the everyday Joe's desktop, thus making MS-DOJ trial irrelevant.

    (Darn Excite, slashdotted again.)

    --
    We want endless gardens of data, where the bits can flower, flourish and reproduce. -- Andy Mueller-Maguhn
  19. Re:What limit have other OS-es? by howardjp · · Score: 2

    FreeBSd has been able to do 4G for many years now.

  20. Re:What limit have other OS-es? by mph · · Score: 2

    FreeBSD on Intel supports 4 GB of RAM. I don't know about Alpha. FreeBSD also supports files of up to 8 TB on FFS. Note that this is considerably longer than 2 GB.