Slashdot Mirror

← Back to Stories (view on slashdot.org)

FreeBSD Looking for People with Lots of RAM

Posted by CowboyNeal on from the not-just-for-ram-drives-anymore dept.

drdink writes "A few weeks ago, PAE (Physical Address Extension) support was added to FreeBSD 5-CURRENT. This allows memory above 4GB to be used normally by the kernel and userland on the x86 platform. Jake Burkholder, the man behind PAE, is now looking for users to help him test this new feature. In his message to the freebsd-current mailing list, Jake describes the current caveats to PAE and also says 'We'd like this feature to be solid for 5.1-RELEASE, so I'm hoping there are people out there with systems with more than 4G of ram that are willing to test it.' This, along with other features make FreeBSD 5-STABLE look very promising."

6 of 271 comments (clear)

  1. Re:Volunteer... by UniverseIsADoughnut · · Score: 5, Informative

    Freebsd does SMP quit well. They have/are redoing the whole SMP system. It was slated for 5.0 but i don't know if it did or did not make it in. When finished Freebsd will have and extremely good SMP, if not the best.

    So what are you crunching with that thing?

  2. Re:Volunteer... by drdink · · Score: 4, Informative
    One thing you need to remember is that FreeBSD 5.x is currently still not -STABLE. This means it is the current development line. There is no guarentee or illusion of stability. That is why such big features as PAE, SMPng, x86-64, etc are being done there. If you are seriously interested in running a development version of FreeBSD, be ready to play a role in debugging, testing, and possibly watching things explode. That said, it has been pretty stable for me lately. If you are still interested, then please do the following:

    For those who are curious about what is new in -CURRENT compared to 4-STABLE, you can read the 5.0-RELEASE release notes for the bits that were new at the time of 5.0-RELEASE. More has come since.

    --
    Beware, Nugget is watching... See?
  3. Re:Volunteer... by drdink · · Score: 5, Informative
    FreeBSD/i386 5.0-RELEASE Release Notes: Processor/Motherboard Support:
    SMP support has been largely reworked, incorporating code from BSD/OS 5.0. One of the main features of SMPng (``SMP Next Generation'') is to allow more processes to run in kernel, without the need for spin locks that can dramatically reduce the efficiency of multiple processors. Interrupt handlers now have contexts associated with them that allow them to be blocked, which reduces the need to lock out interrupts.
    Yes. This is in 5.0 now.
    --
    Beware, Nugget is watching... See?
  4. Re:Sweet! by Guy+Harris · · Score: 4, Informative
    is support for more than 4GB of memory a first for 32-bit x86 operating systems?
    No. The Linux 2.4.x kernel has it, and Unixware 7.1.3 has it (I don't know what release first supported it), and Solaris 7 and later has it as well.

    As others have noted, Windows NT 5.0^H^H^H^H^H^H2000 also supports it.

  5. Re:I have just the box for this... by drdink · · Score: 4, Informative

    FreeBSD supports Hyperthreading in 5.0-CURRENT. There is a sysctl variable called "machdep.hlt_cpus". You can use this variable to control which logical CPUs should be taken out of the idle loop and used by the kernel. This, of course, requires a kernel built with the APIC_IO and SMP kernel options. Lacking a SMP system, I haven't tested this. This is just what I see on the mailing lists and in CVSWeb

    --
    Beware, Nugget is watching... See?
  6. Re:Rembember the LIM standard? by julesh · · Score: 3, Informative

    Years ago, there was the "LIM" (Lotus-Intel-Microsoft) for adding more than 640KB of RAM to a PC, by "windowing in" a section of RAM in a certain area.

    It seems that, 20 years later, we're back to doing essentially the same thing.

    No, this system doesn't work like that.

    Intel processors since the Pentium have supported a system that allows you to use a larger page size than standard so that you can have more physical address space. You specify the start address of each page as 24 bits which are assumed to align to a 4K boundary which gives you 4M*4K = 16Gb of physical RAM. Each page is 2Mb in length. You can mix 4K and 2Mb pages in the same system, although not in the same quarter of the process adress space. So you get more actual physical memory, although each process is limited to 4G at once (whereas with LIM EMS the entire system was limited to 640K + 64K of 'banked' memory)