Re: [PATCH] reorganized per-CPU data

From: Andi Kleen (ak@suse.de)
Date: Fri Jun 16 2000 - 18:38:02 EDT

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    On Fri, Jun 16, 2000 at 02:26:29PM -0700, Dimitris Michailidis wrote:
    > New in this version:
    >
    > - ported to -test1
    > - some more code has been converted to use the new scheme
    > - on MP systems we allocate only as many PDAs as we need.
    >
    > Given that these structures are large (>2K each, larger with IPv6 enabled)
    > the allocation change above can save substantial space on MP systems. On a
    > 4P box space savings amount to more than 79K, .text savings alone exceed 5600
    > bytes (including small savings in the system call and IRQ paths in entry.S ;-)

    Cool :-)

    >
    > Andi Kleen wrote:
    > > Just an ugly problem is the Config dependent layout of the pda data
    > > and module binary compatibility. Maybe it would be possible to tag
    > > some magic symbol with its size and export it, making modules reference
    > > it ?
    >
    > These issues are still present. I don't think exporting the size of a pda is
    > safe, you might be able to get the same size with different configurations.
    > Maybe exporting the offsets of optional fields?

    MODVERSIONS uses a special program that generates function signatures. That
    could be probably extended to the PDA. One easy way would be to store
    a md5 hash of the preprocessed PDA include file.

    -Andi

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