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    SubjectRe: [rfc 00/45] [RFC] CPU ops and a rework of per cpu data handling on x86_64
    n Tue, 20 Nov 2007, Andi Kleen wrote:

    >
    > > Although we have a per-cpu area base in a fixed global register
    > > for addressing, the above isn't beneficial on sparc64 because
    > > the atomic is much slower than doing a:
    > >
    > > local_irq_disable();
    > > nonatomic_percpu_memory_op();
    > > local_irq_enable();
    >
    > Again might be pointing out the obvious, but you
    > need of course save_flags()/restore_flags(), not disable/enable().
    >
    > If it was just disable/enable x86 could do it much faster too
    > and Christoph probably would never felt the need to approach
    > this project for his SLUB fast path.

    I already have no need for that anymore with the material now in Andrews
    tree. However, this cuts out another 6 cycles from the fastpath and I
    found that the same principles reduce overhead all over the kernel.


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