lkml.org 
[lkml]   [2004]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: sched_setaffinity usability
    Ingo Molnar wrote:
    > * Linus Torvalds <torvalds@osdl.org> wrote:
    >
    >
    >>sysconf() is a user-level implementation issue, and so is something
    >>like "number of CPU's". Damn, the simplest way to do it is as a
    >>environment variable, for christ sake! Just make a magic environment
    >>variable called __SC_ARRAY, and make it be some kind of binary
    >>encoding if you worry about performance.
    >
    >
    > i am not arguing for any sysconf() support at all - it clearly belongs
    > into glibc. Just doing 'man sysconf' shows that it should be in
    > user-space. No argument about that.
    >
    > But how about the original issue Ulrich raised: how does user-space
    > figure out the NR_CPUS value supported by the kernel? (not the current #
    > of CPUs, that can be figured out using /proc/cpuinfo)
    >
    > one solution would be what you suggest: to build some sort of /etc/info
    > file that glibc can access, which file is build during the kernel build
    > and contains the necessary constants. One problem with this approach is
    > that a user could boot via any arbitrary kernel, how does glibc (or even
    > a supposed early-init info-setup mechanism) know what info belongs to
    > which kernel? Kernel version numbers are not required to be unique. A
    > single non-modular bzImage can be used to have a fully working
    > userspace. Right now the kernel and glibc is isolated pretty much and
    > this gives us flexibility.

    Let the compile create that info file. Then handle it much like a module,
    except that it is a "module" without any code.
    I.e. copy it to /lib/modules/<kernelversion> if installing modules,
    or stuff the file into the initrd if making an initrd.

    Now it is in a place specific to the kernel, where a library can find it.

    Helge Hafting


    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 14:01    [W:0.021 / U:30.928 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site