[lkml]   [2005]   [Feb]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: A scrub daemon (prezeroing)
    On Wed, 2 Feb 2005, Marcelo Tosatti wrote:

    > Someone should try implementing the zeroing driver for a fast x86 PCI
    > device. :)

    I'm not convinced. Zeroing a page takes 2000-4000 CPU
    cycles, while faulting the page from RAM into cache takes
    200-400 CPU cycles per cache line, or 6000-12000 CPU

    If the page is being used immediately after it is
    allocated, it may be faster to prezero the page on
    the fly. On some CPUs these writes bypass the "read
    from RAM" stage and allow things to just live in cache

    "Debugging is twice as hard as writing the code in the first place.
    Therefore, if you write the code as cleverly as possible, you are,
    by definition, not smart enough to debug it." - Brian W. Kernighan
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 14:10    [W:0.018 / U:11.612 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site