lkml.org 
[lkml]   [2002]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [Lse-tech] Re: 10.31 second kernel compile
    Date
    In article <87wuwfxp25.fsf@fadata.bg>,
    Momchil Velikov <velco@fadata.bg> wrote:
    >
    >Out of curiousity, why there's a need to update the linux page tables ?
    >Doesn't pte/pmd/pgd family functions provide enough abstraction in
    >order to maintain _only_ the hashed page table ?

    No. The IBM hashed page tables are not page tables at all, they are
    really just a bigger 16-way set-associative in-memory TLB.

    You can't actually sanely keep track of VM layout in them.

    Those POWER4 machines are wonderful things, but they have a few quirks:

    - it's so expensive that anybody who is slightly price-conscious gets a
    farm of PC's instead. Oh, well.

    - the CPU module alone is something like .5 kilowatts (translation:
    don't expect it in a nice desktop factor, even if you could afford
    it).

    - IBM nomenclature really is broken. They call disks DASD devices, and
    they call their hash table a page table, and they just confuse
    themselves and everybody else for no good reason. They number bits
    the wrong way around, for example (and big-endian bitordering really
    _is_ clearly inferior to little-endian, unlike byte-ordering. Watch
    the _same_ bits in the _same_ register change name in the 32 vs
    64-bit architecture manuals, and puke)

    But with all their faults, they do have this really studly setup with 8
    big, fast CPU's on a single module. A few of those modules and you get
    some ass-kick performance numbers. As you can see.

    Linus
    -
    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 13:25    [W:0.025 / U:0.644 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site