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    SubjectRe: [PATCH] x86_64: Make NR_IRQS configurable in Kconfig
    On Tuesday 08 August 2006 07:09, Paul Mackerras wrote:
    > Andrew Morton writes:

    [adding linux-arch; talking about doing extensible per cpu areas
    by prereserving virtual space and then later fill it up as needed]

    > > > Drawback would be some more TLB misses.
    > >
    > > yup. On some (important) architectures - I'm not sure which architectures
    > > do the bigpage-for-kernel trick.
    > I looked at optimizing the per-cpu data accessors on PowerPC and only
    > ever saw fractions of a percent change in overall performance, which
    > says to me that we don't actually use per-cpu data all that much. So
    > unless you make per-cpu data really really slow, I doubt that we'll
    > see any significant performance difference.

    The main problem is that we would need a "vmalloc reserve first; allocate pages
    later" interface. On x86 it would be easy by just splitting up vmalloc/vmap a bit
    again. Does anybody else see problems with implementing that on any
    other architecture?

    This wouldn't be truly demand paged, just pages initialized on allocation.


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      Last update: 2006-08-08 07:17    [W:0.020 / U:19.420 seconds]
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